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Sign in with Google Issue
We're having issues getting Sign in with Google to function on TestFlight (not experiencing these issues on iOS Browser) with user unable to be authorised and proceed to logged in screens of our app. Below are the three sign-in methods tested and the exact results for each. Button 1: Default Standard Google Sign-In button (Google JavaScript SDK) embedded in the frontend. Uses the normal OAuth browser redirect flow. Auth URL: https://accounts.google.com/o/oauth2/v2/auth?... Sometimes disallowed_useragent error. Other times a 400 invalid_request error. In most cases the callback is never triggered inside the wrapper. Appears that the wrapper does not retain cookies/session data from the external Google window. Button 2: Custom Custom button calling Google OAuth through our own redirect handler. Explicitly set a custom user-agent to bypass disallowed user agent logic. Later removed user-agent override entirely for testing. Added multiple ATS (App Transport Security) exceptions for Google domains. Added custom URL scheme to Info.plist for OAuth redirect. Changing the user-agent had no effect. ATS exceptions + scheme support verified and working. Redirect still fails to propagate tokens back to the WebView. In tests a few weeks ago we got to Google’s login page, but it never returned to the app with a valid code. Now we are consistently getting disallowed_useragent error. Button 3: Default Same as Button 1 however tested outside of Vue.js with just plain JavaScript. Added new Google domain exceptions and updated redirect URIs. Behaviour matches Button 1 Google account selection sometimes worked, however now consitently disallowed_useragent error Additional Technical Attempts User-Agent Modifications Set UA to standard desktop Chrome → no effect. Removed UA override → no effect. ATS / Domain / Scheme Configuration Added: accounts.google.com .googleusercontent.com *.googleapis.com
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314
Nov ’25
Installer JS warning when try to read the version from /var/db/receipts folder
Hi, I am using Installer JS in Distrtibution file which is created using productbuild command. I am trying to read the installed version of app from the plist file present in the /var/db/receipts folder. It gives the following warning. If I enable the flag , notarization will fail. FJS: Package Authoring Error: access to path "/var/db/receipts/com.xxx.xxx.plist" requires Following is the function I have used to read the installed version. system.files.plistAtPath() I have also tried the following function to read the version from .app file. system.files.bundleAtPath Both the functions give the warning. Is there are a way to avoid this warning or a better way to read the installed version? Regards Prema Kumar
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126
Dec ’25
iPad Pro M4 giving wrong value for layerPointConverted for ultra wide angle
I am using iPad Pro M4 device to apply exposure point to the camera. While converting layerPointConverted from 0 -1 range to device size point it is giving wrong value. But if same code is used for other iPad like Gen2, it gives proper value. In both cases video gravity used is resizeAspectFill. I tried using true depth camera for M4 device but it does not work.
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17m
Gyro/Orientation iframe embed doesn't work on iOS26, works on iOS 18.5
So I'm testing a microapp that is contained in an IPFS folder. I use a web3 website that is used to view NFTs and their IPFS files. The app has gyro controls, which are enabled through a confirmation gesture. In iOS 18.5, when I press "Request Permission" button I get the popup to allow the app to acess movement and orientation. In iOS26, pressing the button does nothing. Keep in mind that this only happens through the website, that uses iframes. When I load the IPFS file from a direct link, the popup appears with no issue. I think this might be because iOS26 uses WebGPU or it might be a bug since iOS26 is still in beta.
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286
Jul ’25
Issue while creating ipa in release mode
I have an MAUI based application build and ready for the distribution. The application is working perfectly in the debug environment on the simulator. So the app logic is working correctly as expected without any errors. But when a release build is created the application crashes on the simulator and physical device. I'm developing the application using .Net 10 framework with target device iOS 26. The Supported OS Platform is set to 15.0 in csproj file. Also have the entitlements. plist file set in the csproj. The IDe used is Visual Studio Code for Mac (MAC OS). The application uses MSAL for the login / authentication purpose (Microsoft.Identity.Client) and SQLite Database (Sqlite-net-pcl) Message: Kindly guide me to build the application correctly in release version and get the ipa file ready for the in house distribution that could be deployed correctly on the physical device with iOS 18 / 26.
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Jan ’26
An Apple Library Primer
Apple’s library technology has a long and glorious history, dating all the way back to the origins of Unix. This does, however, mean that it can be a bit confusing to newcomers. This is my attempt to clarify some terminology. If you have any questions or comments about this, start a new thread and tag it with Linker so that I see it. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" An Apple Library Primer Apple’s tools support two related concepts: Platform — This is the platform itself; macOS, iOS, iOS Simulator, and Mac Catalyst are all platforms. Architecture — This is a specific CPU architecture used by a platform. arm64 and x86_64 are both architectures. A given architecture might be used by multiple platforms. The most obvious example of this arm64, which is used by all of the platforms listed above. Code built for one platform will not work on another platform, even if both platforms use the same architecture. Code is usually packaged in either a Mach-O file or a static library. Mach-O is used for executables (MH_EXECUTE), dynamic libraries (MH_DYLIB), bundles (MH_BUNDLE), and object files (MH_OBJECT). These can have a variety of different extensions; the only constant is that .o is always used for a Mach-O containing an object file. Use otool and nm to examine a Mach-O file. Use vtool to quickly determine the platform for which it was built. Use size to get a summary of its size. Use dyld_info to get more details about a dynamic library. IMPORTANT All the tools mentioned here are documented in man pages. For information on how to access that documentation, see Reading UNIX Manual Pages. There’s also a Mach-O man page, with basic information about the file format. Many of these tools have old and new variants, using the -classic suffix or llvm- prefix, respectively. For example, there’s nm-classic and llvm-nm. If you run the original name for the tool, you’ll get either the old or new variant depending on the version of the currently selected tools. To explicitly request the old or new variants, use xcrun. The term Mach-O image refers to a Mach-O that can be loaded and executed without further processing. That includes executables, dynamic libraries, and bundles, but not object files. A dynamic library has the extension .dylib. You may also see this called a shared library. A framework is a bundle structure with the .framework extension that has both compile-time and run-time roles: At compile time, the framework combines the library’s headers and its stub library (stub libraries are explained below). At run time, the framework combines the library’s code, as a Mach-O dynamic library, and its associated resources. The exact structure of a framework varies by platform. For the details, see Placing Content in a Bundle. macOS supports both frameworks and standalone dynamic libraries. Other Apple platforms support frameworks but not standalone dynamic libraries. Historically these two roles were combined, that is, the framework included the headers, the dynamic library, and its resources. These days Apple ships different frameworks for each role. That is, the macOS SDK includes the compile-time framework and macOS itself includes the run-time one. Most third-party frameworks continue to combine these roles. A static library is an archive of one or more object files. It has the extension .a. Use ar, libtool, and ranlib to inspect and manipulate these archives. The static linker, or just the linker, runs at build time. It combines various inputs into a single output. Typically these inputs are object files, static libraries, dynamic libraries, and various configuration items. The output is most commonly a Mach-O image, although it’s also possible to output an object file. The linker may also output metadata, such as a link map (see Using a Link Map to Track Down a Symbol’s Origin). The linker has seen three major implementations: ld — This dates from the dawn of Mac OS X. ld64 — This was a rewrite started in the 2005 timeframe. Eventually it replaced ld completely. If you type ld, you get ld64. ld_prime — This was introduced with Xcode 15. This isn’t a separate tool. Rather, ld now supports the -ld_classic and -ld_new options to select a specific implementation. Note During the Xcode 15 beta cycle these options were -ld64 and -ld_prime. I continue to use those names because the definition of new changes over time (some of us still think of ld64 as the new linker ;–). The dynamic linker loads Mach-O images at runtime. Its path is /usr/lib/dyld, so it’s often referred to as dyld, dyld, or DYLD. Personally I pronounced that dee-lid, but some folks say di-lid and others say dee-why-el-dee. IMPORTANT Third-party executables must use the standard dynamic linker. Other Unix-y platforms support the notion of a statically linked executable, one that makes system calls directly. This is not supported on Apple platforms. Apple platforms provide binary compatibility via system dynamic libraries and frameworks, not at the system call level. Note Apple platforms have vestigial support for custom dynamic linkers (your executable tells the system which dynamic linker to use via the LC_LOAD_DYLINKER load command). This facility originated on macOS’s ancestor platform and has never been a supported option on any Apple platform. The dynamic linker has seen 4 major revisions. See WWDC 2017 Session 413 (referenced below) for a discussion of versions 1 through 3. Version 4 is basically a merging of versions 2 and 3. The dyld man page is chock-full of useful info, including a discussion of how it finds images at runtime. Every dynamic library has an install name, which is how the dynamic linker identifies the library. Historically that was the path where you installed the library. That’s still true for most system libraries, but nowadays a third-party library should use an rpath-relative install name. For more about this, see Dynamic Library Identification. Mach-O images are position independent, that is, they can be loaded at any location within the process’s address space. Historically, Mach-O supported the concept of position-dependent images, ones that could only be loaded at a specific address. While it may still be possible to create such an image, it’s no longer a good life choice. Mach-O images have a default load address, also known as the base address. For modern position-independent images this is 0 for library images and 4 GiB for executables (leaving the bottom 32 bits of the process’s address space unmapped). When the dynamic linker loads an image, it chooses an address for the image and then rebases the image to that address. If you take that address and subtract the image’s load address, you get a value known as the slide. Xcode 15 introduced the concept of a mergeable library. This a dynamic library with extra metadata that allows the linker to embed it into the output Mach-O image, much like a static library. Mergeable libraries have many benefits. For all the backstory, see WWDC 2023 Session 10268 Meet mergeable libraries. For instructions on how to set this up, see Configuring your project to use mergeable libraries. If you put a mergeable library into a framework structure you get a mergeable framework. Xcode 15 also introduced the concept of a static framework. This is a framework structure where the framework’s dynamic library is replaced by a static library. Note It’s not clear to me whether this offers any benefit over creating a mergeable framework. Earlier versions of Xcode did not have proper static framework support. That didn’t stop folks trying to use them, which caused all sorts of weird build problems. A universal binary is a file that contains multiple architectures for the same platform. Universal binaries always use the universal binary format. Use the file command to learn what architectures are within a universal binary. Use the lipo command to manipulate universal binaries. A universal binary’s architectures are either all in Mach-O format or all in the static library archive format. The latter is called a universal static library. A universal binary has the same extension as its non-universal equivalent. That means a .a file might be a static library or a universal static library. Most tools work on a single architecture within a universal binary. They default to the architecture of the current machine. To override this, pass the architecture in using a command-line option, typically -arch or --arch. An XCFramework is a single document package that includes libraries for any combination of platforms and architectures. It has the extension .xcframework. An XCFramework holds either a framework, a dynamic library, or a static library. All the elements must be the same type. Use xcodebuild to create an XCFramework. For specific instructions, see Xcode Help > Distribute binary frameworks > Create an XCFramework. Historically there was no need to code sign libraries in SDKs. If you shipped an SDK to another developer, they were responsible for re-signing all the code as part of their distribution process. Xcode 15 changes this. You should sign your SDK so that a developer using it can verify this dependency. For more details, see WWDC 2023 Session 10061 Verify app dependencies with digital signatures and Verifying the origin of your XCFrameworks. A stub library is a compact description of the contents of a dynamic library. It has the extension .tbd, which stands for text-based description (TBD). Apple’s SDKs include stub libraries to minimise their size; for the backstory, read this post. Use the tapi tool to create and manipulate stub libraries. In this context TAPI stands for a text-based API, an alternative name for TBD. Oh, and on the subject of tapi, I’d be remiss if I didn’t mention tapi-analyze! Stub libraries currently use YAML format, a fact that’s relevant when you try to interpret linker errors. If you’re curious about the format, read the tapi-tbdv4 man page. There’s also a JSON variant documented in the tapi-tbdv5 man page. Note Back in the day stub libraries used to be Mach-O files with all the code removed (MH_DYLIB_STUB). This format has long been deprecated in favour of TBD. Historically, the system maintained a dynamic linker shared cache, built at runtime from its working set of dynamic libraries. In macOS 11 and later this cache is included in the OS itself. Libraries in the cache are no longer present in their original locations on disk: % ls -lh /usr/lib/libSystem.B.dylib ls: /usr/lib/libSystem.B.dylib: No such file or directory Apple APIs, most notably dlopen, understand this and do the right thing if you supply the path of a library that moved into the cache. That’s true for some, but not all, command-line tools, for example: % dyld_info -exports /usr/lib/libSystem.B.dylib /usr/lib/libSystem.B.dylib [arm64e]: -exports: offset symbol … 0x5B827FE8 _mach_init_routine % nm /usr/lib/libSystem.B.dylib …/nm: error: /usr/lib/libSystem.B.dylib: No such file or directory When the linker creates a Mach-O image, it adds a bunch of helpful information to that image, including: The target platform The deployment target, that is, the minimum supported version of that platform Information about the tools used to build the image, most notably, the SDK version A build UUID For more information about the build UUID, see TN3178 Checking for and resolving build UUID problems. To dump the other information, run vtool. In some cases the OS uses the SDK version of the main executable to determine whether to enable new behaviour or retain old behaviour for compatibility purposes. You might see this referred to as compiled against SDK X. I typically refer to this as a linked-on-or-later check. Apple tools support the concept of autolinking. When your code uses a symbol from a module, the compiler inserts a reference (using the LC_LINKER_OPTION load command) to that module into the resulting object file (.o). When you link with that object file, the linker adds the referenced module to the list of modules that it searches when resolving symbols. Autolinking is obviously helpful but it can also cause problems, especially with cross-platform code. For information on how to enable and disable it, see the Build settings reference. Mach-O uses a two-level namespace. When a Mach-O image imports a symbol, it references the symbol name and the library where it expects to find that symbol. This improves both performance and reliability but it precludes certain techniques that might work on other platforms. For example, you can’t define a function called printf and expect it to ‘see’ calls from other dynamic libraries because those libraries import the version of printf from libSystem. To help folks who rely on techniques like this, macOS supports a flat namespace compatibility mode. This has numerous sharp edges — for an example, see the posts on this thread — and it’s best to avoid it where you can. If you’re enabling the flat namespace as part of a developer tool, search the ’net for dyld interpose to learn about an alternative technique. WARNING Dynamic linker interposing is not documented as API. While it’s a useful technique for developer tools, do not use it in products you ship to end users. Apple platforms use DWARF. When you compile a file, the compiler puts the debug info into the resulting object file. When you link a set of object files into a executable, dynamic library, or bundle for distribution, the linker does not include this debug info. Rather, debug info is stored in a separate debug symbols document package. This has the extension .dSYM and is created using dsymutil. Use symbols to learn about the symbols in a file. Use dwarfdump to get detailed information about DWARF debug info. Use atos to map an address to its corresponding symbol name. Different languages use different name mangling schemes: C, and all later languages, add a leading underscore (_) to distinguish their symbols from assembly language symbols. C++ uses a complex name mangling scheme. Use the c++filt tool to undo this mangling. Likewise, for Swift. Use swift demangle to undo this mangling. For a bunch more info about symbols in Mach-O, see Understanding Mach-O Symbols. This includes a discussion of weak references and weak definition. If your code is referencing a symbol unexpectedly, see Determining Why a Symbol is Referenced. To remove symbols from a Mach-O file, run strip. To hide symbols, run nmedit. It’s common for linkers to divide an object file into sections. You might find data in the data section and code in the text section (text is an old Unix term for code). Mach-O uses segments and sections. For example, there is a text segment (__TEXT) and within that various sections for code (__TEXT > __text), constant C strings (__TEXT > __cstring), and so on. Over the years there have been some really good talks about linking and libraries at WWDC, including: WWDC 2023 Session 10268 Meet mergeable libraries WWDC 2022 Session 110362 Link fast: Improve build and launch times WWDC 2022 Session 110370 Debug Swift debugging with LLDB WWDC 2021 Session 10211 Symbolication: Beyond the basics WWDC 2019 Session 416 Binary Frameworks in Swift — Despite the name, this covers XCFrameworks in depth. WWDC 2018 Session 415 Behind the Scenes of the Xcode Build Process WWDC 2017 Session 413 App Startup Time: Past, Present, and Future WWDC 2016 Session 406 Optimizing App Startup Time Note The older talks are no longer available from Apple, but you may be able to find transcripts out there on the ’net. Historically Apple published a document, Mac OS X ABI Mach-O File Format Reference, or some variant thereof, that acted as the definitive reference to the Mach-O file format. This document is no longer available from Apple. If you’re doing serious work with Mach-O, I recommend that you find an old copy. It’s definitely out of date, but there’s no better place to get a high-level introduction to the concepts. The Mach-O Wikipedia page has a link to an archived version of the document. For the most up-to-date information about Mach-O, see the declarations and doc comments in <mach-o/loader.h>. Revision History 2025-08-04 Added a link to Determining Why a Symbol is Referenced. 2025-06-29 Added information about autolinking. 2025-05-21 Added a note about the legacy Mach-O stub library format (MH_DYLIB_STUB). 2025-04-30 Added a specific reference to the man pages for the TBD format. 2025-03-01 Added a link to Understanding Mach-O Symbols. Added a link to TN3178 Checking for and resolving build UUID problems. Added a summary of the information available via vtool. Discussed linked-on-or-later checks. Explained how Mach-O uses segments and sections. Explained the old (-classic) and new (llvm-) tool variants. Referenced the Mach-O man page. Added basic info about the strip and nmedit tools. 2025-02-17 Expanded the discussion of dynamic library identification. 2024-10-07 Added some basic information about the dynamic linker shared cache. 2024-07-26 Clarified the description of the expected load address for Mach-O images. 2024-07-23 Added a discussion of position-independent images and the image slide. 2024-05-08 Added links to the demangling tools. 2024-04-30 Clarified the requirement to use the standard dynamic linker. 2024-03-02 Updated the discussion of static frameworks to account for Xcode 15 changes. Removed the link to WWDC 2018 Session 415 because it no longer works )-: 2024-03-01 Added the WWDC 2023 session to the list of sessions to make it easier to find. Added a reference to Using a Link Map to Track Down a Symbol’s Origin. Made other minor editorial changes. 2023-09-20 Added a link to Dynamic Library Identification. Updated the names for the static linker implementations (-ld_prime is no more!). Removed the beta epithet from Xcode 15. 2023-06-13 Defined the term Mach-O image. Added sections for both the static and dynamic linkers. Described the two big new features in Xcode 15: mergeable libraries and dependency verification. 2023-06-01 Add a reference to tapi-analyze. 2023-05-29 Added a discussion of the two-level namespace. 2023-04-27 Added a mention of the size tool. 2023-01-23 Explained the compile-time and run-time roles of a framework. Made other minor editorial changes. 2022-11-17 Added an explanation of TAPI. 2022-10-12 Added links to Mach-O documentation. 2022-09-29 Added info about .dSYM files. Added a few more links to WWDC sessions. 2022-09-21 First posted.
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16k
Aug ’25
Localizing your apps
TL;DR version: AkVox - “Your App in Your User’s Language” Quickly and easily localize your app into as few or as many languages as you want with AkVox. Longer version: AkVox can localize any Xcode project. Simply drag your Exported Localizations folder into AkVox, click translate, then export, and you’re ready to import the translated localizations catalogs back into Xcode. Alas, you cannot import the whole localizations folder as one, you must import each catalog individually, a process that takes around 10 seconds per language. AkVox can also assist you when you’re ready to publish your app on App Store Connect. You can create a list of texts you will enter to promote your app and AkVox will translate them. Again, you can’t apply all your translations to the App Store in ne go, you have to apply each language individually. To make this task less painful, AkVox has a convenient set of buttons to make the copy and paste process as quick and simple as possible. The same arrangement is available when you come to add “mini texts” during setting monetization subscriptions. AkVox employs Google Cloud Translate which means you will need an API Key to be able to run full translations. However, Google offers a generous monthly allowance of 500,000 characters to be translated for free each month. This may well mean that you don’t ever pay for the translation process, just the very low price to use AkVox. The free version of AkVox simulates translating by substituting jumbled versions of Hamlet’s “To be or not to be” speech – this is instead of utilising what would normally be used in this case, the tediously dull Lorem Ipsum text. To see AkVox explained in detail, go to the website: https://akvox.com/
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114
Aug ’25
How to install cocoapods and pod
Hi, I am developing IOS(Android App) with React Native. I am very confused about cocoapods and pod and how to correctly install it on my new Macbook Pro M4. I am not using bash but I am using zsh. Note, actuallywhich pod return nothing During the preparation of my environment, it say CocoaPods is one of the dependency management system available for iOS. CocoaPods is a Ruby gem. You can install CocoaPods using the version of Ruby that ships with the latest version of macOS. the web site show two commands gem install cocoapods sudo gem install cocoapods I saw another command as well brew install cocoapods During different processes, I experienced several time the following error (Command 'pod install failed) Command pod install failed. └─ Cause: pod install --repo-update --ansi exited with non-zero code: 1 Then I am confused about cocoapods and pod. Are both he same? With my previous MacBook pro, I spend time to install cocoapod on my profile because Ruby was not the latest version on the system. But apparently, on my new Macbook Pro M4, the command ruby -v return (as well) ruby 2.6.10p210 (2022-04-12 revision 67958) [universal.arm64e-darwin25] The current stable version is 4.0.0. I bought a new macbook pro M4 and I reinstalled node and all package for Rect Native 0.81 a expo 54 excepted cocoapods. Now, I need to configure the push notification and it's time to install cocoapods as it's require here But on my new macbook pro, I would like to make sure I do it correctly and I kindly ask your help and recommandation to install Ruby and cocoapods/pod Q1: Should I install cocoapods with brew install cocoapods or gem install cocoapods? Q2: what's is the difference or the common point with cocoapods and pod? Cocoapod web site said If using the default Ruby included with macOS, installation will require you to use sudo when installing gems As ruby -v print 'ruby 2.6.10p210', I suppose, I should not install cocoapod with sudo You can use a Ruby Version manager such as RVM or rbenv to manage multiple Ruby versions, or you can use Homebrew to install a newer Ruby with brew install ruby. As far I understand, I should not install cocoapods with the Ruby version of the system, then I suppose the command Q3: Will 'brew install cocopads' install the latest version on my profile? Will it upgrade the system version Q4: What will do the command brew install rbenv ruby-build rbenv install 3.2.2 (or better: rbenv install 4.0.0) in comparison with brew install ruby My guess I suppose that the following will help, but it would nice if you could correct me and clarify # All should be done in my profile brew install rbenv ruby-build echo 'eval "$(rbenv init - bash)"' >> ~/.zprofile source ~/.zprofile rbenv install 4.0.0 # rbenv global 4.0.0 # What is it? ruby -v gem install cocoapods Q5: But then, what about pod and the error message Command pod install failed. As you can see, I am a bit confused and I would appreciate your clarification I thanks you for your help and clarification and I wish you a happy new years
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244
Jan ’26
[Unreal Engine] File missing if packaged with command line
Hello! I am trying to automate iOS builds for my Unreal Engine game using Unreal Automation Tool, but I cannot produce a functionnal build with it, while packaging from XCode works perfectly. I have tracked down the issue to a missing file. I'm using the Firebase SDK that requires a GoogleService-Info.plist file. I have copied this file at the root of my project, as the Firebase documentation suggests. I have not taken any manual action to specify that this file needs to be included in the packaged app. The Firebase code checks the existence of this file using NSString* Path = [[NSBundle mainBundle] pathForResource: @“GoogleService-Info” ofType: @“plist”]; return Path != nil; If I package my app from XCode using Product -> Archive, this test returns true and the SDK is properly initialized. If I package my app using Unreal Engine's RunUAT.sh BuildCookRun, this test returns false and the SDK fails to initialize (and actually crashes upon trying). I have tried several Unreal Engine tricks to include my file, like setting it as a RuntimeDependecies in my projects Build.cs file. Which enables Unreal Engine code to find it, but not this direct call to NSBundle. I would like to know either how to tell Unreal Engine to include files at the root of the app bundle, or what XCode does to automatically include this file and is there a way to script it? I can provide both versions .xcarchive if needed. Thanks!
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155
Sep ’25
SwiftMacros Not able to access of main project XCTest File.
I have developed a Swift macro called @CodableInit in the SwiftCodableMacro module, and I’m able to use it successfully in my main project. Here’s an example usage: import SwiftCodableMacro @CodableInit // This is for Codable macros public class ErrorMonitoringWebPlugin { public var identifier: UUID = UUID() // MARK: - Codable required public init(from decoder:Decoder) throws { let values = try decoder.container(keyedBy: CodingKeys.self) identifier = try values.decode(UUID.self, forKey: .identifier) } } However, when I try to write a unit test for the ErrorMonitoringWebPlugin class, I encounter an issue. Here's the test case: func testCodableSubjectIdentifierShouldEqualDecodedSubjectIdentifier() { self.measure { let encoder = JSONEncoder() let data = try? encoder.encode(subject) //Here I am getting this error Class 'JSONEncoder' requires that 'ErrorMonitoringWebPlugin' conform to 'Encodable' let decoder = JSONDecoder() let decodedSubject = try? decoder.decode(ErrorMonitoringWebPlugin.self, from: data!) XCTAssertEqual(subject.identifier, decodedSubject?.identifier) } } The compiler throws an error saying: Class 'JSONEncoder' requires that 'ErrorMonitoringWebPlugin' conform to 'Encodable' Even though the @CodableInit macro is supposed to generate conformance, it seems that this macro-generated code is not visible or active inside the test target. How can I ensure that the @CodableInit macro (from SwiftCodableMacro) is correctly applied and recognized within the XCTest target of my main project?
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95
Jun ’25
Inconsistent results involving code signatures and bundles
I admit I am doing something unusual, and I would not be surprised if it didn't work. I am surprised, however, because after performing the equivalent operations on four bundles, all of the bundles work fine on macOS 15.6.1, but only two of them work on macOS 26.1 (beta 2). I don't know what causes the different outcomes. What I am trying to do is get Java to pass the macOS 26 AppKit UI SDK linkage checking without having to rebuild the JDK using Xcode 26. Rebuilding works for the latest SDK, but it is very inconvenient and may not work for older JDKs. It usually takes a while before the JDK build team successfully transitions to a new Xcode release. My approach is to use vtool to update the sdk version in the LC_BUILD_VERSION load command of $JAVA_HOME/bin/java, which is the launching executable for the JDK. I performed this operation on four JDKs: 25, 21, 17, and 11. (I ran vtool on macOS 15.) It was completely successful on JDK 25 and 21. The JDK launches correctly on macOS 15 and macOS 26. On macOS 26, AppKit uses the new UI, which is the desired outcome. The JDK runs despite that fact that I signed the modified $JAVA_HOME/bin/java with my developer ID, which is inconsistent with the JDK bundle signature. (Redoing the bundle signing is part of the JDK build process; if that were necessary, I would stick with rebuilding the JDK.) The operation was not successful on JDK 17 and 11. I noticed two problems, which are not obviously related. When vtool created the new version of the java program, it lost the tool definition. $ vtool -show-build-version java java: Load command 10 cmd LC_BUILD_VERSION cmdsize 32 platform MACOS minos 11.0 sdk 11.1 ntools 1 tool LD version 609.8 $ vtool -set-build-version 1 10.0 26.0 -output a.out java /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/vtool warning: code signature will be invalid for a.out $ vtool -show-build-version a.out a.out: Load command 22 cmd LC_BUILD_VERSION cmdsize 24 platform MACOS minos 10.0 sdk 26.0 ntools 0 Adding back the tool definition didn't seem to matter. When I try to run the revised executable (in the context of the JDK bundle), it works on macOS 15, but on macOS 26, it is rejected as damaged. If I run the revised executable outside the JDK bundle, it runs (but fails because it can't find the rest of the JDK, which is expected). In all cases, GateKeeper rejects the revised executable because it has not been notarized, but that doesn't seem to stop the program from executing.
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261
Oct ’25
What is the unit used for the availableKilobytes property of the target object?
In the online documentation for InstallerJS, it is stated that the unit for the availableKilobytes property of the target field is kilobytes. Isn't it actually bytes because of a bug in the very first release of macOS that supported InstallerJS? [Q] Has there been a fix in the recent years regarding this property that would explain why the documentation says it's kilobytes? Even though at the time of this writing, the unit is still bytes when you call my.target.availableKilobytes I'm using this call to dump the value of this property in install.log: system.log(my.target.availableKilobytes + ''); Ref. https://developer.apple.com/documentation/installer_js/target/1811975-availablekilobytes (FB20448952)
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Sep ’25
Trouble setting up watches to use TestFlight that are AWFK configured
I am developing a simple watch app and I use my personal watch for development with Xcode. Personal watch is series 10 gps only. I have two other watches that I want to use for testing the app, but not needing them to be connected to Xcode. The test watches have cellular option, and I need a cell plan per watch because the watches need to be standalone, not counting initial setup. To get the standalone cell plan the watches need to be configured using AWFK. Here is what I have tried/current issues. I switch between all three watches on my phone using the watch app. Originally tried to put test watches in developer mode, thinking I would connect to Xcode, developer mode is not available when watch is setup using AWFK. Pushed the watch app to apple connect, setup TestFlight group, added the test users and my phone user, accepted invites TestFlight is installed on my phone, I see the testflight setup for the watch app I set a test watch using watch app on the phone, run install for the test app from TestFlight on the phone, spinner moves for awhile then goes back to Install. I am not able to get the watch app installed on the test watches from the phone. Is what I am attempting to do supported? I haven't found much specific documentation on this. If I pair the test watches as regular watches, set them to developer mode, can I pair them again as AWFK and will developer mode survive the switch? Or is there something really simple that I'm overlooking? Appreciate any help that can be extended.
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Dec ’25
Determining Why a Symbol is Referenced
Recently a bunch of folks have asked about why a specific symbol is being referenced by their app. This is my attempt to address that question. If you have questions or comments, please start a new thread. Tag it with Linker so that I see it. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Determining Why a Symbol is Referenced In some situations you might want to know why a symbol is referenced by your app. For example: You might be working with a security auditing tool that flags uses of malloc. You might be creating a privacy manifest and want to track down where your app is calling stat. This post is my attempt at explaining a general process for tracking down the origin of these symbol references. This process works from ‘below’. That is, it works ‘up’ from you app’s binary rather than ‘down’ from your app’s source code. That’s important because: It might be hard to track down all of your source code, especially if you’re using one or more package management systems. If your app has a binary dependency on a static library, dynamic library, or framework, you might not have access to that library’s source code. IMPORTANT This post assumes the terminology from An Apple Library Primer. Read that before continuing here. The general outline of this process is: Find all Mach-O images. Find the Mach-O image that references the symbol. Find the object files (.o) used to make that Mach-O. Find the object file that references the symbol. Find the code within that object file. Those last few steps require some gnarly low-level Mach-O knowledge. If you’re looking for an easier path, try using the approach described in the A higher-level alternative section as a replacement for steps 3 through 5. This post assumes that you’re using Xcode. If you’re using third-party tools that are based on Apple tools, and specifically Apple’s linker, you should be able to adapt this process to your tooling. If you’re using a third-party tool that has its own linker, you’ll need to ask for help via your tool’s support channel. Find all Mach-O images On Apple platforms an app consists of a number of Mach-O images. Every app has a main executable. The app may also embed dynamic libraries or frameworks. The app may also embed app extensions or system extensions, each of which have their own executable. And a Mac app might have embedded bundles, helper tools, XPC services, agents, daemons, and so on. To find all the Mach-O images in your app, combine the find and file tools. For example: % find "Apple Configurator.app" -print0 | xargs -0 file | grep Mach-O Apple Configurator.app/Contents/MacOS/Apple Configurator: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64] [arm64] … Apple Configurator.app/Contents/MacOS/cfgutil: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64] [arm64:Mach-O 64-bit executable arm64] … Apple Configurator.app/Contents/Extensions/ConfiguratorIntents.appex/Contents/MacOS/ConfiguratorIntents: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64] [arm64:Mach-O 64-bit executable arm64] … Apple Configurator.app/Contents/Frameworks/ConfigurationUtilityKit.framework/Versions/A/ConfigurationUtilityKit: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit dynamically linked shared library x86_64] [arm64] … This shows that Apple Configurator has a main executable (Apple Configurator), a helper tool (cfgutil), an app extension (ConfiguratorIntents), a framework (ConfigurationUtilityKit), and many more. This output is quite unwieldy. For nicer output, create and use a shell script like this: % cat FindMachO.sh #! /bin/sh # Passing `-0` to `find` causes it to emit a NUL delimited after the # file name and the `:`. Sadly, macOS `cut` doesn’t support a nul # delimiter so we use `tr` to convert that to a DLE (0x01) and `cut` on # that. # # Weirdly, `find` only inserts the NUL on the primary line, not the # per-architecture Mach-O lines. We use that to our advantage, filtering # out the per-architecture noise by only passing through lines # containing a DLE. find "$@" -type f -print0 \ | xargs -0 file -0 \ | grep -a Mach-O \ | tr '\0' '\1' \ | grep -a $(printf '\1') \ | cut -d $(printf '\1') -f 1 Find the Mach-O image that references the symbol Once you have a list of Mach-O images, use nm to find the one that references the symbol. The rest of this post investigate a test app, WaffleVarnishORama, that’s written in Swift but uses waffle management functionality from the libWaffleCore.a static library. The goal is to find the code that calls calloc. This app has a single Mach-O image: % FindMachO.sh "WaffleVarnishORama.app" WaffleVarnishORama.app/WaffleVarnishORama Use nm to confirm that it references calloc: % nm "WaffleVarnishORama.app/WaffleVarnishORama" | grep "calloc" U _calloc The _calloc symbol has a leading underscore because it’s a C symbol. This convention dates from the dawn of Unix, where the underscore distinguish C symbols from assembly language symbols. The U prefix indicates that the symbol is undefined, that is, the Mach-O images is importing the symbol. If the symbol name is prefixed by a hex number and some other character, like T or t, that means that the library includes an implementation of calloc. That’s weird, but certainly possible. OTOH, if you see this then you know this Mach-O image isn’t importing calloc. IMPORTANT If this Mach-O isn’t something that you build — that is, you get this Mach-O image as a binary from another developer — you won’t be able to follow the rest of this process. Instead, ask for help via that library’s support channel. Find the object files used to make that Mach-O image The next step is to track down which .o file includes the reference to calloc. Do this by generating a link map. A link map is an old school linker feature that records the location, size, and origin of every symbol added to the linker’s output. To generate a link map, enable the Write Link Map File build setting. By default this puts the link map into a text (.txt) file within the derived data directory. To find the exact path, look at the Link step in the build log. If you want to customise this, use the Path to Link Map File build setting. A link map has three parts: A simple header A list of object files used to build the Mach-O image A list of sections and their symbols In our case the link map looks like this: # Path: …/WaffleVarnishORama.app/WaffleVarnishORama # Arch: arm64 # Object files: [ 0] linker synthesized [ 1] objc-file [ 2] …/AppDelegate.o [ 3] …/MainViewController.o [ 4] …/libWaffleCore.a[2](WaffleCore.o) [ 5] …/Foundation.framework/Foundation.tbd … # Sections: # Address Size Segment Section 0x100008000 0x00001AB8 __TEXT __text … The list of object files contains: An object file for each of our app’s source files — That’s AppDelegate.o and MainViewController.o in this example. A list of static libraries — Here that’s just libWaffleCore.a. A list of dynamic libraries — These might be stub libraries (.tbd), dynamic libraries (.dylib), or frameworks (.framework). Focus on the object files and static libraries. The list of dynamic libraries is irrelevant because each of those is its own Mach-O image. Find the object file that references the symbol Once you have list of object files and static libraries, use nm to each one for the calloc symbol: % nm "…/AppDelegate.o" | grep calloc % nm "…/MainViewController.o" | grep calloc % nm "…/libWaffleCore.a" | grep calloc U _calloc This indicates that only libWaffleCore.a references the calloc symbol, so let’s focus on that. Note As in the Mach-O case, the U prefix indicates that the symbol is undefined, that is, the object file is importing the symbol. Find the code within that object file To find the code within the object file that references the symbol, use the objdump tool. That tool takes an object file as input, but in this example we have a static library. That’s an archive containing one or more object files. So, the first step is to unpack that archive: % mkdir "libWaffleCore-objects" % cd "libWaffleCore-objects" % ar -x "…/libWaffleCore.a" % ls -lh total 24 -rw-r--r-- 1 quinn staff 4.1K 8 May 11:24 WaffleCore.o -rw-r--r-- 1 quinn staff 56B 8 May 11:24 __.SYMDEF SORTED There’s only a single object file in that library, which makes things easy. If there were a multiple, run the following process over each one independently. To find the code that references a symbol, run objdump with the -S and -r options: % xcrun objdump -S -r "WaffleCore.o" … ; extern WaffleRef newWaffle(void) { 0: d10083ff sub sp, sp, #32 4: a9017bfd stp x29, x30, [sp, #16] 8: 910043fd add x29, sp, #16 c: d2800020 mov x0, #1 10: d2800081 mov x1, #4 ; Waffle * result = calloc(1, sizeof(Waffle)); 14: 94000000 bl 0x14 <ltmp0+0x14> 0000000000000014: ARM64_RELOC_BRANCH26 _calloc … Note the ARM64_RELOC_BRANCH26 line. This tells you that the instruction before that — the bl at offset 0x14 — references the _calloc symbol. IMPORTANT The ARM64_RELOC_BRANCH26 relocation is specific to the bl instruction in 64-bit Arm code. You’ll see other relocations for other instructions. And the Intel architecture has a whole different set of relocations. So, when searching this output don’t look for ARM64_RELOC_BRANCH26 specifically, but rather any relocation that references _calloc. In this case we’ve built the object file from source code, so WaffleCore.o contains debug symbols. That allows objdump include information about the source code context. From that, we can easily see that calloc is referenced by our newWaffle function. To see what happens when you don’t have debug symbols, create an new object file with them stripped out: % cp "WaffleCore.o" "WaffleCore-stripped.o" % strip -x -S "WaffleCore-stripped.o" Then repeat the objdump command: % xcrun objdump -S -r "WaffleCore-stripped.o" … 0000000000000000 <_newWaffle>: 0: d10083ff sub sp, sp, #32 4: a9017bfd stp x29, x30, [sp, #16] 8: 910043fd add x29, sp, #16 c: d2800020 mov x0, #1 10: d2800081 mov x1, #4 14: 94000000 bl 0x14 <_newWaffle+0x14> 0000000000000014: ARM64_RELOC_BRANCH26 _calloc … While this isn’t as nice as the previous output, you can still see that newWaffle is calling calloc. A higher-level alternative Grovelling through Mach-O object files is quite tricky. Fortunately there’s an easier approach: Use the -why_live option to ask the linker why it included a reference to the symbol. To continue the above example, I set the Other Linker Flags build setting to -Xlinker / -why_live / -Xlinker / _calloc and this is what I saw in the build transcript: _calloc from /usr/lib/system/libsystem_malloc.dylib _newWaffle from …/libWaffleCore.a[2](WaffleCore.o) _$s18WaffleVarnishORama18MainViewControllerC05tableE0_14didSelectRowAtySo07UITableE0C_10Foundation9IndexPathVtFTf4dnn_n from …/MainViewController.o _$s18WaffleVarnishORama18MainViewControllerC05tableE0_14didSelectRowAtySo07UITableE0C_10Foundation9IndexPathVtF from …/MainViewController.o Demangling reveals a call chain like this: calloc newWaffle WaffleVarnishORama.MainViewController.tableView(_:didSelectRowAt:) WaffleVarnishORama.MainViewController.tableView(_:didSelectRowAt:) and that should be enough to kick start your investigation. IMPORTANT The -why_live option only works if you dead strip your Mach-O image. This is the default for the Release build configuration, so use that for this test. Revision History 2025-07-18 Added the A higher-level alternative section. 2024-05-08 First posted.
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1.4k
Jul ’25
Sign in with Google Issue
We're having issues getting Sign in with Google to function on TestFlight (not experiencing these issues on iOS Browser) with user unable to be authorised and proceed to logged in screens of our app. Below are the three sign-in methods tested and the exact results for each. Button 1: Default Standard Google Sign-In button (Google JavaScript SDK) embedded in the frontend. Uses the normal OAuth browser redirect flow. Auth URL: https://accounts.google.com/o/oauth2/v2/auth?... Sometimes disallowed_useragent error. Other times a 400 invalid_request error. In most cases the callback is never triggered inside the wrapper. Appears that the wrapper does not retain cookies/session data from the external Google window. Button 2: Custom Custom button calling Google OAuth through our own redirect handler. Explicitly set a custom user-agent to bypass disallowed user agent logic. Later removed user-agent override entirely for testing. Added multiple ATS (App Transport Security) exceptions for Google domains. Added custom URL scheme to Info.plist for OAuth redirect. Changing the user-agent had no effect. ATS exceptions + scheme support verified and working. Redirect still fails to propagate tokens back to the WebView. In tests a few weeks ago we got to Google’s login page, but it never returned to the app with a valid code. Now we are consistently getting disallowed_useragent error. Button 3: Default Same as Button 1 however tested outside of Vue.js with just plain JavaScript. Added new Google domain exceptions and updated redirect URIs. Behaviour matches Button 1 Google account selection sometimes worked, however now consitently disallowed_useragent error Additional Technical Attempts User-Agent Modifications Set UA to standard desktop Chrome → no effect. Removed UA override → no effect. ATS / Domain / Scheme Configuration Added: accounts.google.com .googleusercontent.com *.googleapis.com
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0
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314
Activity
Nov ’25
Installer JS warning when try to read the version from /var/db/receipts folder
Hi, I am using Installer JS in Distrtibution file which is created using productbuild command. I am trying to read the installed version of app from the plist file present in the /var/db/receipts folder. It gives the following warning. If I enable the flag , notarization will fail. FJS: Package Authoring Error: access to path "/var/db/receipts/com.xxx.xxx.plist" requires Following is the function I have used to read the installed version. system.files.plistAtPath() I have also tried the following function to read the version from .app file. system.files.bundleAtPath Both the functions give the warning. Is there are a way to avoid this warning or a better way to read the installed version? Regards Prema Kumar
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1
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126
Activity
Dec ’25
iPad Pro M4 giving wrong value for layerPointConverted for ultra wide angle
I am using iPad Pro M4 device to apply exposure point to the camera. While converting layerPointConverted from 0 -1 range to device size point it is giving wrong value. But if same code is used for other iPad like Gen2, it gives proper value. In both cases video gravity used is resizeAspectFill. I tried using true depth camera for M4 device but it does not work.
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5
Activity
17m
Gyro/Orientation iframe embed doesn't work on iOS26, works on iOS 18.5
So I'm testing a microapp that is contained in an IPFS folder. I use a web3 website that is used to view NFTs and their IPFS files. The app has gyro controls, which are enabled through a confirmation gesture. In iOS 18.5, when I press "Request Permission" button I get the popup to allow the app to acess movement and orientation. In iOS26, pressing the button does nothing. Keep in mind that this only happens through the website, that uses iframes. When I load the IPFS file from a direct link, the popup appears with no issue. I think this might be because iOS26 uses WebGPU or it might be a bug since iOS26 is still in beta.
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0
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286
Activity
Jul ’25
How to pick which simulator i want to use in xcode
currently i'm in xcode 26.2 which want's me to use ios 26.2 but i only have ios 18.2 and i can't figure out how to make xcode use that simulator
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1
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103
Activity
Feb ’26
.NET(NativeAOT)
在将游戏从 Nintendo Switch 移植到 Mac 的过程中使用 .NET (NativeAOT) 有哪些限制和注意事项(尽管两者都是 ARM)?
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128
Activity
Jun ’25
Issue while creating ipa in release mode
I have an MAUI based application build and ready for the distribution. The application is working perfectly in the debug environment on the simulator. So the app logic is working correctly as expected without any errors. But when a release build is created the application crashes on the simulator and physical device. I'm developing the application using .Net 10 framework with target device iOS 26. The Supported OS Platform is set to 15.0 in csproj file. Also have the entitlements. plist file set in the csproj. The IDe used is Visual Studio Code for Mac (MAC OS). The application uses MSAL for the login / authentication purpose (Microsoft.Identity.Client) and SQLite Database (Sqlite-net-pcl) Message: Kindly guide me to build the application correctly in release version and get the ipa file ready for the in house distribution that could be deployed correctly on the physical device with iOS 18 / 26.
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64
Activity
Jan ’26
An Apple Library Primer
Apple’s library technology has a long and glorious history, dating all the way back to the origins of Unix. This does, however, mean that it can be a bit confusing to newcomers. This is my attempt to clarify some terminology. If you have any questions or comments about this, start a new thread and tag it with Linker so that I see it. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" An Apple Library Primer Apple’s tools support two related concepts: Platform — This is the platform itself; macOS, iOS, iOS Simulator, and Mac Catalyst are all platforms. Architecture — This is a specific CPU architecture used by a platform. arm64 and x86_64 are both architectures. A given architecture might be used by multiple platforms. The most obvious example of this arm64, which is used by all of the platforms listed above. Code built for one platform will not work on another platform, even if both platforms use the same architecture. Code is usually packaged in either a Mach-O file or a static library. Mach-O is used for executables (MH_EXECUTE), dynamic libraries (MH_DYLIB), bundles (MH_BUNDLE), and object files (MH_OBJECT). These can have a variety of different extensions; the only constant is that .o is always used for a Mach-O containing an object file. Use otool and nm to examine a Mach-O file. Use vtool to quickly determine the platform for which it was built. Use size to get a summary of its size. Use dyld_info to get more details about a dynamic library. IMPORTANT All the tools mentioned here are documented in man pages. For information on how to access that documentation, see Reading UNIX Manual Pages. There’s also a Mach-O man page, with basic information about the file format. Many of these tools have old and new variants, using the -classic suffix or llvm- prefix, respectively. For example, there’s nm-classic and llvm-nm. If you run the original name for the tool, you’ll get either the old or new variant depending on the version of the currently selected tools. To explicitly request the old or new variants, use xcrun. The term Mach-O image refers to a Mach-O that can be loaded and executed without further processing. That includes executables, dynamic libraries, and bundles, but not object files. A dynamic library has the extension .dylib. You may also see this called a shared library. A framework is a bundle structure with the .framework extension that has both compile-time and run-time roles: At compile time, the framework combines the library’s headers and its stub library (stub libraries are explained below). At run time, the framework combines the library’s code, as a Mach-O dynamic library, and its associated resources. The exact structure of a framework varies by platform. For the details, see Placing Content in a Bundle. macOS supports both frameworks and standalone dynamic libraries. Other Apple platforms support frameworks but not standalone dynamic libraries. Historically these two roles were combined, that is, the framework included the headers, the dynamic library, and its resources. These days Apple ships different frameworks for each role. That is, the macOS SDK includes the compile-time framework and macOS itself includes the run-time one. Most third-party frameworks continue to combine these roles. A static library is an archive of one or more object files. It has the extension .a. Use ar, libtool, and ranlib to inspect and manipulate these archives. The static linker, or just the linker, runs at build time. It combines various inputs into a single output. Typically these inputs are object files, static libraries, dynamic libraries, and various configuration items. The output is most commonly a Mach-O image, although it’s also possible to output an object file. The linker may also output metadata, such as a link map (see Using a Link Map to Track Down a Symbol’s Origin). The linker has seen three major implementations: ld — This dates from the dawn of Mac OS X. ld64 — This was a rewrite started in the 2005 timeframe. Eventually it replaced ld completely. If you type ld, you get ld64. ld_prime — This was introduced with Xcode 15. This isn’t a separate tool. Rather, ld now supports the -ld_classic and -ld_new options to select a specific implementation. Note During the Xcode 15 beta cycle these options were -ld64 and -ld_prime. I continue to use those names because the definition of new changes over time (some of us still think of ld64 as the new linker ;–). The dynamic linker loads Mach-O images at runtime. Its path is /usr/lib/dyld, so it’s often referred to as dyld, dyld, or DYLD. Personally I pronounced that dee-lid, but some folks say di-lid and others say dee-why-el-dee. IMPORTANT Third-party executables must use the standard dynamic linker. Other Unix-y platforms support the notion of a statically linked executable, one that makes system calls directly. This is not supported on Apple platforms. Apple platforms provide binary compatibility via system dynamic libraries and frameworks, not at the system call level. Note Apple platforms have vestigial support for custom dynamic linkers (your executable tells the system which dynamic linker to use via the LC_LOAD_DYLINKER load command). This facility originated on macOS’s ancestor platform and has never been a supported option on any Apple platform. The dynamic linker has seen 4 major revisions. See WWDC 2017 Session 413 (referenced below) for a discussion of versions 1 through 3. Version 4 is basically a merging of versions 2 and 3. The dyld man page is chock-full of useful info, including a discussion of how it finds images at runtime. Every dynamic library has an install name, which is how the dynamic linker identifies the library. Historically that was the path where you installed the library. That’s still true for most system libraries, but nowadays a third-party library should use an rpath-relative install name. For more about this, see Dynamic Library Identification. Mach-O images are position independent, that is, they can be loaded at any location within the process’s address space. Historically, Mach-O supported the concept of position-dependent images, ones that could only be loaded at a specific address. While it may still be possible to create such an image, it’s no longer a good life choice. Mach-O images have a default load address, also known as the base address. For modern position-independent images this is 0 for library images and 4 GiB for executables (leaving the bottom 32 bits of the process’s address space unmapped). When the dynamic linker loads an image, it chooses an address for the image and then rebases the image to that address. If you take that address and subtract the image’s load address, you get a value known as the slide. Xcode 15 introduced the concept of a mergeable library. This a dynamic library with extra metadata that allows the linker to embed it into the output Mach-O image, much like a static library. Mergeable libraries have many benefits. For all the backstory, see WWDC 2023 Session 10268 Meet mergeable libraries. For instructions on how to set this up, see Configuring your project to use mergeable libraries. If you put a mergeable library into a framework structure you get a mergeable framework. Xcode 15 also introduced the concept of a static framework. This is a framework structure where the framework’s dynamic library is replaced by a static library. Note It’s not clear to me whether this offers any benefit over creating a mergeable framework. Earlier versions of Xcode did not have proper static framework support. That didn’t stop folks trying to use them, which caused all sorts of weird build problems. A universal binary is a file that contains multiple architectures for the same platform. Universal binaries always use the universal binary format. Use the file command to learn what architectures are within a universal binary. Use the lipo command to manipulate universal binaries. A universal binary’s architectures are either all in Mach-O format or all in the static library archive format. The latter is called a universal static library. A universal binary has the same extension as its non-universal equivalent. That means a .a file might be a static library or a universal static library. Most tools work on a single architecture within a universal binary. They default to the architecture of the current machine. To override this, pass the architecture in using a command-line option, typically -arch or --arch. An XCFramework is a single document package that includes libraries for any combination of platforms and architectures. It has the extension .xcframework. An XCFramework holds either a framework, a dynamic library, or a static library. All the elements must be the same type. Use xcodebuild to create an XCFramework. For specific instructions, see Xcode Help > Distribute binary frameworks > Create an XCFramework. Historically there was no need to code sign libraries in SDKs. If you shipped an SDK to another developer, they were responsible for re-signing all the code as part of their distribution process. Xcode 15 changes this. You should sign your SDK so that a developer using it can verify this dependency. For more details, see WWDC 2023 Session 10061 Verify app dependencies with digital signatures and Verifying the origin of your XCFrameworks. A stub library is a compact description of the contents of a dynamic library. It has the extension .tbd, which stands for text-based description (TBD). Apple’s SDKs include stub libraries to minimise their size; for the backstory, read this post. Use the tapi tool to create and manipulate stub libraries. In this context TAPI stands for a text-based API, an alternative name for TBD. Oh, and on the subject of tapi, I’d be remiss if I didn’t mention tapi-analyze! Stub libraries currently use YAML format, a fact that’s relevant when you try to interpret linker errors. If you’re curious about the format, read the tapi-tbdv4 man page. There’s also a JSON variant documented in the tapi-tbdv5 man page. Note Back in the day stub libraries used to be Mach-O files with all the code removed (MH_DYLIB_STUB). This format has long been deprecated in favour of TBD. Historically, the system maintained a dynamic linker shared cache, built at runtime from its working set of dynamic libraries. In macOS 11 and later this cache is included in the OS itself. Libraries in the cache are no longer present in their original locations on disk: % ls -lh /usr/lib/libSystem.B.dylib ls: /usr/lib/libSystem.B.dylib: No such file or directory Apple APIs, most notably dlopen, understand this and do the right thing if you supply the path of a library that moved into the cache. That’s true for some, but not all, command-line tools, for example: % dyld_info -exports /usr/lib/libSystem.B.dylib /usr/lib/libSystem.B.dylib [arm64e]: -exports: offset symbol … 0x5B827FE8 _mach_init_routine % nm /usr/lib/libSystem.B.dylib …/nm: error: /usr/lib/libSystem.B.dylib: No such file or directory When the linker creates a Mach-O image, it adds a bunch of helpful information to that image, including: The target platform The deployment target, that is, the minimum supported version of that platform Information about the tools used to build the image, most notably, the SDK version A build UUID For more information about the build UUID, see TN3178 Checking for and resolving build UUID problems. To dump the other information, run vtool. In some cases the OS uses the SDK version of the main executable to determine whether to enable new behaviour or retain old behaviour for compatibility purposes. You might see this referred to as compiled against SDK X. I typically refer to this as a linked-on-or-later check. Apple tools support the concept of autolinking. When your code uses a symbol from a module, the compiler inserts a reference (using the LC_LINKER_OPTION load command) to that module into the resulting object file (.o). When you link with that object file, the linker adds the referenced module to the list of modules that it searches when resolving symbols. Autolinking is obviously helpful but it can also cause problems, especially with cross-platform code. For information on how to enable and disable it, see the Build settings reference. Mach-O uses a two-level namespace. When a Mach-O image imports a symbol, it references the symbol name and the library where it expects to find that symbol. This improves both performance and reliability but it precludes certain techniques that might work on other platforms. For example, you can’t define a function called printf and expect it to ‘see’ calls from other dynamic libraries because those libraries import the version of printf from libSystem. To help folks who rely on techniques like this, macOS supports a flat namespace compatibility mode. This has numerous sharp edges — for an example, see the posts on this thread — and it’s best to avoid it where you can. If you’re enabling the flat namespace as part of a developer tool, search the ’net for dyld interpose to learn about an alternative technique. WARNING Dynamic linker interposing is not documented as API. While it’s a useful technique for developer tools, do not use it in products you ship to end users. Apple platforms use DWARF. When you compile a file, the compiler puts the debug info into the resulting object file. When you link a set of object files into a executable, dynamic library, or bundle for distribution, the linker does not include this debug info. Rather, debug info is stored in a separate debug symbols document package. This has the extension .dSYM and is created using dsymutil. Use symbols to learn about the symbols in a file. Use dwarfdump to get detailed information about DWARF debug info. Use atos to map an address to its corresponding symbol name. Different languages use different name mangling schemes: C, and all later languages, add a leading underscore (_) to distinguish their symbols from assembly language symbols. C++ uses a complex name mangling scheme. Use the c++filt tool to undo this mangling. Likewise, for Swift. Use swift demangle to undo this mangling. For a bunch more info about symbols in Mach-O, see Understanding Mach-O Symbols. This includes a discussion of weak references and weak definition. If your code is referencing a symbol unexpectedly, see Determining Why a Symbol is Referenced. To remove symbols from a Mach-O file, run strip. To hide symbols, run nmedit. It’s common for linkers to divide an object file into sections. You might find data in the data section and code in the text section (text is an old Unix term for code). Mach-O uses segments and sections. For example, there is a text segment (__TEXT) and within that various sections for code (__TEXT > __text), constant C strings (__TEXT > __cstring), and so on. Over the years there have been some really good talks about linking and libraries at WWDC, including: WWDC 2023 Session 10268 Meet mergeable libraries WWDC 2022 Session 110362 Link fast: Improve build and launch times WWDC 2022 Session 110370 Debug Swift debugging with LLDB WWDC 2021 Session 10211 Symbolication: Beyond the basics WWDC 2019 Session 416 Binary Frameworks in Swift — Despite the name, this covers XCFrameworks in depth. WWDC 2018 Session 415 Behind the Scenes of the Xcode Build Process WWDC 2017 Session 413 App Startup Time: Past, Present, and Future WWDC 2016 Session 406 Optimizing App Startup Time Note The older talks are no longer available from Apple, but you may be able to find transcripts out there on the ’net. Historically Apple published a document, Mac OS X ABI Mach-O File Format Reference, or some variant thereof, that acted as the definitive reference to the Mach-O file format. This document is no longer available from Apple. If you’re doing serious work with Mach-O, I recommend that you find an old copy. It’s definitely out of date, but there’s no better place to get a high-level introduction to the concepts. The Mach-O Wikipedia page has a link to an archived version of the document. For the most up-to-date information about Mach-O, see the declarations and doc comments in <mach-o/loader.h>. Revision History 2025-08-04 Added a link to Determining Why a Symbol is Referenced. 2025-06-29 Added information about autolinking. 2025-05-21 Added a note about the legacy Mach-O stub library format (MH_DYLIB_STUB). 2025-04-30 Added a specific reference to the man pages for the TBD format. 2025-03-01 Added a link to Understanding Mach-O Symbols. Added a link to TN3178 Checking for and resolving build UUID problems. Added a summary of the information available via vtool. Discussed linked-on-or-later checks. Explained how Mach-O uses segments and sections. Explained the old (-classic) and new (llvm-) tool variants. Referenced the Mach-O man page. Added basic info about the strip and nmedit tools. 2025-02-17 Expanded the discussion of dynamic library identification. 2024-10-07 Added some basic information about the dynamic linker shared cache. 2024-07-26 Clarified the description of the expected load address for Mach-O images. 2024-07-23 Added a discussion of position-independent images and the image slide. 2024-05-08 Added links to the demangling tools. 2024-04-30 Clarified the requirement to use the standard dynamic linker. 2024-03-02 Updated the discussion of static frameworks to account for Xcode 15 changes. Removed the link to WWDC 2018 Session 415 because it no longer works )-: 2024-03-01 Added the WWDC 2023 session to the list of sessions to make it easier to find. Added a reference to Using a Link Map to Track Down a Symbol’s Origin. Made other minor editorial changes. 2023-09-20 Added a link to Dynamic Library Identification. Updated the names for the static linker implementations (-ld_prime is no more!). Removed the beta epithet from Xcode 15. 2023-06-13 Defined the term Mach-O image. Added sections for both the static and dynamic linkers. Described the two big new features in Xcode 15: mergeable libraries and dependency verification. 2023-06-01 Add a reference to tapi-analyze. 2023-05-29 Added a discussion of the two-level namespace. 2023-04-27 Added a mention of the size tool. 2023-01-23 Explained the compile-time and run-time roles of a framework. Made other minor editorial changes. 2022-11-17 Added an explanation of TAPI. 2022-10-12 Added links to Mach-O documentation. 2022-09-29 Added info about .dSYM files. Added a few more links to WWDC sessions. 2022-09-21 First posted.
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Aug ’25
Localizing your apps
TL;DR version: AkVox - “Your App in Your User’s Language” Quickly and easily localize your app into as few or as many languages as you want with AkVox. Longer version: AkVox can localize any Xcode project. Simply drag your Exported Localizations folder into AkVox, click translate, then export, and you’re ready to import the translated localizations catalogs back into Xcode. Alas, you cannot import the whole localizations folder as one, you must import each catalog individually, a process that takes around 10 seconds per language. AkVox can also assist you when you’re ready to publish your app on App Store Connect. You can create a list of texts you will enter to promote your app and AkVox will translate them. Again, you can’t apply all your translations to the App Store in ne go, you have to apply each language individually. To make this task less painful, AkVox has a convenient set of buttons to make the copy and paste process as quick and simple as possible. The same arrangement is available when you come to add “mini texts” during setting monetization subscriptions. AkVox employs Google Cloud Translate which means you will need an API Key to be able to run full translations. However, Google offers a generous monthly allowance of 500,000 characters to be translated for free each month. This may well mean that you don’t ever pay for the translation process, just the very low price to use AkVox. The free version of AkVox simulates translating by substituting jumbled versions of Hamlet’s “To be or not to be” speech – this is instead of utilising what would normally be used in this case, the tediously dull Lorem Ipsum text. To see AkVox explained in detail, go to the website: https://akvox.com/
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Aug ’25
How to install cocoapods and pod
Hi, I am developing IOS(Android App) with React Native. I am very confused about cocoapods and pod and how to correctly install it on my new Macbook Pro M4. I am not using bash but I am using zsh. Note, actuallywhich pod return nothing During the preparation of my environment, it say CocoaPods is one of the dependency management system available for iOS. CocoaPods is a Ruby gem. You can install CocoaPods using the version of Ruby that ships with the latest version of macOS. the web site show two commands gem install cocoapods sudo gem install cocoapods I saw another command as well brew install cocoapods During different processes, I experienced several time the following error (Command 'pod install failed) Command pod install failed. └─ Cause: pod install --repo-update --ansi exited with non-zero code: 1 Then I am confused about cocoapods and pod. Are both he same? With my previous MacBook pro, I spend time to install cocoapod on my profile because Ruby was not the latest version on the system. But apparently, on my new Macbook Pro M4, the command ruby -v return (as well) ruby 2.6.10p210 (2022-04-12 revision 67958) [universal.arm64e-darwin25] The current stable version is 4.0.0. I bought a new macbook pro M4 and I reinstalled node and all package for Rect Native 0.81 a expo 54 excepted cocoapods. Now, I need to configure the push notification and it's time to install cocoapods as it's require here But on my new macbook pro, I would like to make sure I do it correctly and I kindly ask your help and recommandation to install Ruby and cocoapods/pod Q1: Should I install cocoapods with brew install cocoapods or gem install cocoapods? Q2: what's is the difference or the common point with cocoapods and pod? Cocoapod web site said If using the default Ruby included with macOS, installation will require you to use sudo when installing gems As ruby -v print 'ruby 2.6.10p210', I suppose, I should not install cocoapod with sudo You can use a Ruby Version manager such as RVM or rbenv to manage multiple Ruby versions, or you can use Homebrew to install a newer Ruby with brew install ruby. As far I understand, I should not install cocoapods with the Ruby version of the system, then I suppose the command Q3: Will 'brew install cocopads' install the latest version on my profile? Will it upgrade the system version Q4: What will do the command brew install rbenv ruby-build rbenv install 3.2.2 (or better: rbenv install 4.0.0) in comparison with brew install ruby My guess I suppose that the following will help, but it would nice if you could correct me and clarify # All should be done in my profile brew install rbenv ruby-build echo 'eval "$(rbenv init - bash)"' >> ~/.zprofile source ~/.zprofile rbenv install 4.0.0 # rbenv global 4.0.0 # What is it? ruby -v gem install cocoapods Q5: But then, what about pod and the error message Command pod install failed. As you can see, I am a bit confused and I would appreciate your clarification I thanks you for your help and clarification and I wish you a happy new years
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Jan ’26
[Unreal Engine] File missing if packaged with command line
Hello! I am trying to automate iOS builds for my Unreal Engine game using Unreal Automation Tool, but I cannot produce a functionnal build with it, while packaging from XCode works perfectly. I have tracked down the issue to a missing file. I'm using the Firebase SDK that requires a GoogleService-Info.plist file. I have copied this file at the root of my project, as the Firebase documentation suggests. I have not taken any manual action to specify that this file needs to be included in the packaged app. The Firebase code checks the existence of this file using NSString* Path = [[NSBundle mainBundle] pathForResource: @“GoogleService-Info” ofType: @“plist”]; return Path != nil; If I package my app from XCode using Product -> Archive, this test returns true and the SDK is properly initialized. If I package my app using Unreal Engine's RunUAT.sh BuildCookRun, this test returns false and the SDK fails to initialize (and actually crashes upon trying). I have tried several Unreal Engine tricks to include my file, like setting it as a RuntimeDependecies in my projects Build.cs file. Which enables Unreal Engine code to find it, but not this direct call to NSBundle. I would like to know either how to tell Unreal Engine to include files at the root of the app bundle, or what XCode does to automatically include this file and is there a way to script it? I can provide both versions .xcarchive if needed. Thanks!
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Sep ’25
I can't create key for apn file
i am trying to create key for apn file to use it in firebase fcm for my app but when click on download this error occured Download Failed Auth Key can only be downloaded once. This auth key has already been downloaded. what should i do ?
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Sep ’25
Developer Runtime Missing for iOS 26 Beta
unable to find developer runtimes in this list https://developer.apple.com/download/all/?q=simulator%20runtime also, can see it's not being published since iOS 18.2 release, any specific reasons for it? or is the download link changed here?
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Jun ’25
Weatherkit - quota usage
where can i find the account quota usage for WeatherAPI?
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109
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Apr ’25
SwiftMacros Not able to access of main project XCTest File.
I have developed a Swift macro called @CodableInit in the SwiftCodableMacro module, and I’m able to use it successfully in my main project. Here’s an example usage: import SwiftCodableMacro @CodableInit // This is for Codable macros public class ErrorMonitoringWebPlugin { public var identifier: UUID = UUID() // MARK: - Codable required public init(from decoder:Decoder) throws { let values = try decoder.container(keyedBy: CodingKeys.self) identifier = try values.decode(UUID.self, forKey: .identifier) } } However, when I try to write a unit test for the ErrorMonitoringWebPlugin class, I encounter an issue. Here's the test case: func testCodableSubjectIdentifierShouldEqualDecodedSubjectIdentifier() { self.measure { let encoder = JSONEncoder() let data = try? encoder.encode(subject) //Here I am getting this error Class 'JSONEncoder' requires that 'ErrorMonitoringWebPlugin' conform to 'Encodable' let decoder = JSONDecoder() let decodedSubject = try? decoder.decode(ErrorMonitoringWebPlugin.self, from: data!) XCTAssertEqual(subject.identifier, decodedSubject?.identifier) } } The compiler throws an error saying: Class 'JSONEncoder' requires that 'ErrorMonitoringWebPlugin' conform to 'Encodable' Even though the @CodableInit macro is supposed to generate conformance, it seems that this macro-generated code is not visible or active inside the test target. How can I ensure that the @CodableInit macro (from SwiftCodableMacro) is correctly applied and recognized within the XCTest target of my main project?
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Jun ’25
Inconsistent results involving code signatures and bundles
I admit I am doing something unusual, and I would not be surprised if it didn't work. I am surprised, however, because after performing the equivalent operations on four bundles, all of the bundles work fine on macOS 15.6.1, but only two of them work on macOS 26.1 (beta 2). I don't know what causes the different outcomes. What I am trying to do is get Java to pass the macOS 26 AppKit UI SDK linkage checking without having to rebuild the JDK using Xcode 26. Rebuilding works for the latest SDK, but it is very inconvenient and may not work for older JDKs. It usually takes a while before the JDK build team successfully transitions to a new Xcode release. My approach is to use vtool to update the sdk version in the LC_BUILD_VERSION load command of $JAVA_HOME/bin/java, which is the launching executable for the JDK. I performed this operation on four JDKs: 25, 21, 17, and 11. (I ran vtool on macOS 15.) It was completely successful on JDK 25 and 21. The JDK launches correctly on macOS 15 and macOS 26. On macOS 26, AppKit uses the new UI, which is the desired outcome. The JDK runs despite that fact that I signed the modified $JAVA_HOME/bin/java with my developer ID, which is inconsistent with the JDK bundle signature. (Redoing the bundle signing is part of the JDK build process; if that were necessary, I would stick with rebuilding the JDK.) The operation was not successful on JDK 17 and 11. I noticed two problems, which are not obviously related. When vtool created the new version of the java program, it lost the tool definition. $ vtool -show-build-version java java: Load command 10 cmd LC_BUILD_VERSION cmdsize 32 platform MACOS minos 11.0 sdk 11.1 ntools 1 tool LD version 609.8 $ vtool -set-build-version 1 10.0 26.0 -output a.out java /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/vtool warning: code signature will be invalid for a.out $ vtool -show-build-version a.out a.out: Load command 22 cmd LC_BUILD_VERSION cmdsize 24 platform MACOS minos 10.0 sdk 26.0 ntools 0 Adding back the tool definition didn't seem to matter. When I try to run the revised executable (in the context of the JDK bundle), it works on macOS 15, but on macOS 26, it is rejected as damaged. If I run the revised executable outside the JDK bundle, it runs (but fails because it can't find the rest of the JDK, which is expected). In all cases, GateKeeper rejects the revised executable because it has not been notarized, but that doesn't seem to stop the program from executing.
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Oct ’25
What is the unit used for the availableKilobytes property of the target object?
In the online documentation for InstallerJS, it is stated that the unit for the availableKilobytes property of the target field is kilobytes. Isn't it actually bytes because of a bug in the very first release of macOS that supported InstallerJS? [Q] Has there been a fix in the recent years regarding this property that would explain why the documentation says it's kilobytes? Even though at the time of this writing, the unit is still bytes when you call my.target.availableKilobytes I'm using this call to dump the value of this property in install.log: system.log(my.target.availableKilobytes + ''); Ref. https://developer.apple.com/documentation/installer_js/target/1811975-availablekilobytes (FB20448952)
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Sep ’25
Trouble setting up watches to use TestFlight that are AWFK configured
I am developing a simple watch app and I use my personal watch for development with Xcode. Personal watch is series 10 gps only. I have two other watches that I want to use for testing the app, but not needing them to be connected to Xcode. The test watches have cellular option, and I need a cell plan per watch because the watches need to be standalone, not counting initial setup. To get the standalone cell plan the watches need to be configured using AWFK. Here is what I have tried/current issues. I switch between all three watches on my phone using the watch app. Originally tried to put test watches in developer mode, thinking I would connect to Xcode, developer mode is not available when watch is setup using AWFK. Pushed the watch app to apple connect, setup TestFlight group, added the test users and my phone user, accepted invites TestFlight is installed on my phone, I see the testflight setup for the watch app I set a test watch using watch app on the phone, run install for the test app from TestFlight on the phone, spinner moves for awhile then goes back to Install. I am not able to get the watch app installed on the test watches from the phone. Is what I am attempting to do supported? I haven't found much specific documentation on this. If I pair the test watches as regular watches, set them to developer mode, can I pair them again as AWFK and will developer mode survive the switch? Or is there something really simple that I'm overlooking? Appreciate any help that can be extended.
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Dec ’25
Determining Why a Symbol is Referenced
Recently a bunch of folks have asked about why a specific symbol is being referenced by their app. This is my attempt to address that question. If you have questions or comments, please start a new thread. Tag it with Linker so that I see it. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Determining Why a Symbol is Referenced In some situations you might want to know why a symbol is referenced by your app. For example: You might be working with a security auditing tool that flags uses of malloc. You might be creating a privacy manifest and want to track down where your app is calling stat. This post is my attempt at explaining a general process for tracking down the origin of these symbol references. This process works from ‘below’. That is, it works ‘up’ from you app’s binary rather than ‘down’ from your app’s source code. That’s important because: It might be hard to track down all of your source code, especially if you’re using one or more package management systems. If your app has a binary dependency on a static library, dynamic library, or framework, you might not have access to that library’s source code. IMPORTANT This post assumes the terminology from An Apple Library Primer. Read that before continuing here. The general outline of this process is: Find all Mach-O images. Find the Mach-O image that references the symbol. Find the object files (.o) used to make that Mach-O. Find the object file that references the symbol. Find the code within that object file. Those last few steps require some gnarly low-level Mach-O knowledge. If you’re looking for an easier path, try using the approach described in the A higher-level alternative section as a replacement for steps 3 through 5. This post assumes that you’re using Xcode. If you’re using third-party tools that are based on Apple tools, and specifically Apple’s linker, you should be able to adapt this process to your tooling. If you’re using a third-party tool that has its own linker, you’ll need to ask for help via your tool’s support channel. Find all Mach-O images On Apple platforms an app consists of a number of Mach-O images. Every app has a main executable. The app may also embed dynamic libraries or frameworks. The app may also embed app extensions or system extensions, each of which have their own executable. And a Mac app might have embedded bundles, helper tools, XPC services, agents, daemons, and so on. To find all the Mach-O images in your app, combine the find and file tools. For example: % find "Apple Configurator.app" -print0 | xargs -0 file | grep Mach-O Apple Configurator.app/Contents/MacOS/Apple Configurator: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64] [arm64] … Apple Configurator.app/Contents/MacOS/cfgutil: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64] [arm64:Mach-O 64-bit executable arm64] … Apple Configurator.app/Contents/Extensions/ConfiguratorIntents.appex/Contents/MacOS/ConfiguratorIntents: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64] [arm64:Mach-O 64-bit executable arm64] … Apple Configurator.app/Contents/Frameworks/ConfigurationUtilityKit.framework/Versions/A/ConfigurationUtilityKit: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit dynamically linked shared library x86_64] [arm64] … This shows that Apple Configurator has a main executable (Apple Configurator), a helper tool (cfgutil), an app extension (ConfiguratorIntents), a framework (ConfigurationUtilityKit), and many more. This output is quite unwieldy. For nicer output, create and use a shell script like this: % cat FindMachO.sh #! /bin/sh # Passing `-0` to `find` causes it to emit a NUL delimited after the # file name and the `:`. Sadly, macOS `cut` doesn’t support a nul # delimiter so we use `tr` to convert that to a DLE (0x01) and `cut` on # that. # # Weirdly, `find` only inserts the NUL on the primary line, not the # per-architecture Mach-O lines. We use that to our advantage, filtering # out the per-architecture noise by only passing through lines # containing a DLE. find "$@" -type f -print0 \ | xargs -0 file -0 \ | grep -a Mach-O \ | tr '\0' '\1' \ | grep -a $(printf '\1') \ | cut -d $(printf '\1') -f 1 Find the Mach-O image that references the symbol Once you have a list of Mach-O images, use nm to find the one that references the symbol. The rest of this post investigate a test app, WaffleVarnishORama, that’s written in Swift but uses waffle management functionality from the libWaffleCore.a static library. The goal is to find the code that calls calloc. This app has a single Mach-O image: % FindMachO.sh "WaffleVarnishORama.app" WaffleVarnishORama.app/WaffleVarnishORama Use nm to confirm that it references calloc: % nm "WaffleVarnishORama.app/WaffleVarnishORama" | grep "calloc" U _calloc The _calloc symbol has a leading underscore because it’s a C symbol. This convention dates from the dawn of Unix, where the underscore distinguish C symbols from assembly language symbols. The U prefix indicates that the symbol is undefined, that is, the Mach-O images is importing the symbol. If the symbol name is prefixed by a hex number and some other character, like T or t, that means that the library includes an implementation of calloc. That’s weird, but certainly possible. OTOH, if you see this then you know this Mach-O image isn’t importing calloc. IMPORTANT If this Mach-O isn’t something that you build — that is, you get this Mach-O image as a binary from another developer — you won’t be able to follow the rest of this process. Instead, ask for help via that library’s support channel. Find the object files used to make that Mach-O image The next step is to track down which .o file includes the reference to calloc. Do this by generating a link map. A link map is an old school linker feature that records the location, size, and origin of every symbol added to the linker’s output. To generate a link map, enable the Write Link Map File build setting. By default this puts the link map into a text (.txt) file within the derived data directory. To find the exact path, look at the Link step in the build log. If you want to customise this, use the Path to Link Map File build setting. A link map has three parts: A simple header A list of object files used to build the Mach-O image A list of sections and their symbols In our case the link map looks like this: # Path: …/WaffleVarnishORama.app/WaffleVarnishORama # Arch: arm64 # Object files: [ 0] linker synthesized [ 1] objc-file [ 2] …/AppDelegate.o [ 3] …/MainViewController.o [ 4] …/libWaffleCore.a[2](WaffleCore.o) [ 5] …/Foundation.framework/Foundation.tbd … # Sections: # Address Size Segment Section 0x100008000 0x00001AB8 __TEXT __text … The list of object files contains: An object file for each of our app’s source files — That’s AppDelegate.o and MainViewController.o in this example. A list of static libraries — Here that’s just libWaffleCore.a. A list of dynamic libraries — These might be stub libraries (.tbd), dynamic libraries (.dylib), or frameworks (.framework). Focus on the object files and static libraries. The list of dynamic libraries is irrelevant because each of those is its own Mach-O image. Find the object file that references the symbol Once you have list of object files and static libraries, use nm to each one for the calloc symbol: % nm "…/AppDelegate.o" | grep calloc % nm "…/MainViewController.o" | grep calloc % nm "…/libWaffleCore.a" | grep calloc U _calloc This indicates that only libWaffleCore.a references the calloc symbol, so let’s focus on that. Note As in the Mach-O case, the U prefix indicates that the symbol is undefined, that is, the object file is importing the symbol. Find the code within that object file To find the code within the object file that references the symbol, use the objdump tool. That tool takes an object file as input, but in this example we have a static library. That’s an archive containing one or more object files. So, the first step is to unpack that archive: % mkdir "libWaffleCore-objects" % cd "libWaffleCore-objects" % ar -x "…/libWaffleCore.a" % ls -lh total 24 -rw-r--r-- 1 quinn staff 4.1K 8 May 11:24 WaffleCore.o -rw-r--r-- 1 quinn staff 56B 8 May 11:24 __.SYMDEF SORTED There’s only a single object file in that library, which makes things easy. If there were a multiple, run the following process over each one independently. To find the code that references a symbol, run objdump with the -S and -r options: % xcrun objdump -S -r "WaffleCore.o" … ; extern WaffleRef newWaffle(void) { 0: d10083ff sub sp, sp, #32 4: a9017bfd stp x29, x30, [sp, #16] 8: 910043fd add x29, sp, #16 c: d2800020 mov x0, #1 10: d2800081 mov x1, #4 ; Waffle * result = calloc(1, sizeof(Waffle)); 14: 94000000 bl 0x14 <ltmp0+0x14> 0000000000000014: ARM64_RELOC_BRANCH26 _calloc … Note the ARM64_RELOC_BRANCH26 line. This tells you that the instruction before that — the bl at offset 0x14 — references the _calloc symbol. IMPORTANT The ARM64_RELOC_BRANCH26 relocation is specific to the bl instruction in 64-bit Arm code. You’ll see other relocations for other instructions. And the Intel architecture has a whole different set of relocations. So, when searching this output don’t look for ARM64_RELOC_BRANCH26 specifically, but rather any relocation that references _calloc. In this case we’ve built the object file from source code, so WaffleCore.o contains debug symbols. That allows objdump include information about the source code context. From that, we can easily see that calloc is referenced by our newWaffle function. To see what happens when you don’t have debug symbols, create an new object file with them stripped out: % cp "WaffleCore.o" "WaffleCore-stripped.o" % strip -x -S "WaffleCore-stripped.o" Then repeat the objdump command: % xcrun objdump -S -r "WaffleCore-stripped.o" … 0000000000000000 <_newWaffle>: 0: d10083ff sub sp, sp, #32 4: a9017bfd stp x29, x30, [sp, #16] 8: 910043fd add x29, sp, #16 c: d2800020 mov x0, #1 10: d2800081 mov x1, #4 14: 94000000 bl 0x14 <_newWaffle+0x14> 0000000000000014: ARM64_RELOC_BRANCH26 _calloc … While this isn’t as nice as the previous output, you can still see that newWaffle is calling calloc. A higher-level alternative Grovelling through Mach-O object files is quite tricky. Fortunately there’s an easier approach: Use the -why_live option to ask the linker why it included a reference to the symbol. To continue the above example, I set the Other Linker Flags build setting to -Xlinker / -why_live / -Xlinker / _calloc and this is what I saw in the build transcript: _calloc from /usr/lib/system/libsystem_malloc.dylib _newWaffle from …/libWaffleCore.a[2](WaffleCore.o) _$s18WaffleVarnishORama18MainViewControllerC05tableE0_14didSelectRowAtySo07UITableE0C_10Foundation9IndexPathVtFTf4dnn_n from …/MainViewController.o _$s18WaffleVarnishORama18MainViewControllerC05tableE0_14didSelectRowAtySo07UITableE0C_10Foundation9IndexPathVtF from …/MainViewController.o Demangling reveals a call chain like this: calloc newWaffle WaffleVarnishORama.MainViewController.tableView(_:didSelectRowAt:) WaffleVarnishORama.MainViewController.tableView(_:didSelectRowAt:) and that should be enough to kick start your investigation. IMPORTANT The -why_live option only works if you dead strip your Mach-O image. This is the default for the Release build configuration, so use that for this test. Revision History 2025-07-18 Added the A higher-level alternative section. 2024-05-08 First posted.
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