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Programming Languages Resources
This topic area is about the programming languages themselves, not about any specific API or tool. If you have an API question, go to the top level and look for a subtopic for that API. If you have a question about Apple developer tools, start in the Developer Tools & Services topic. For Swift questions: If your question is about the SwiftUI framework, start in UI Frameworks > SwiftUI. If your question is specific to the Swift Playground app, ask over in Developer Tools & Services > Swift Playground If you’re interested in the Swift open source effort — that includes the evolution of the language, the open source tools and libraries, and Swift on non-Apple platforms — check out Swift Forums If your question is about the Swift language, that’s on topic for Programming Languages > Swift, but you might have more luck asking it in Swift Forums > Using Swift. General: Forums topic: Programming Languages Swift: Forums subtopic: Programming Languages > Swift Forums tags: Swift Developer > Swift website Swift Programming Language website The Swift Programming Language documentation Swift Forums website, and specifically Swift Forums > Using Swift Swift Package Index website Concurrency Resources, which covers Swift concurrency How to think properly about binding memory Swift Forums thread Other: Forums subtopic: Programming Languages > Generic Forums tags: Objective-C Programming with Objective-C archived documentation Objective-C Runtime documentation Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"
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1.7k
Oct ’25
Bridging Headers is unsupported or Module compiled with Swift 5.5.1 cannot be imported by the Swift 5.6 complier
Hello guys! I faced a problem with building... My device suddenly updated to iOS 15.4.1, my Xcode was 13.2 and I had to update it to the latest version (13.3.1) to build the app. After the update, I had a few problems which were successfully solved but one of them stopped me for a few hours. The problem is with Bridging Headers or Swift Compiler, I really don't know what I did badly, and what causes problems. On several forums I often read that is important to set: Build Settings > Build Options > Build Libraries for Distribution But in any case it doesn't work, on yes: error: using bridging headers with module interfaces is unsupported on no: (line with import framework SWXMLHash) /Users/blablabla/SSLModel.swift:9:8: error: module compiled with Swift 5.5.1 cannot be imported by the Swift 5.6 compiler: /Users/blablabla2/Build/Products/Debug-iphoneos/SWXMLHash.framework/Modules/SWXMLHash.swiftmodule/arm64-apple-ios.swiftmodule import SWXMLHash It will be important that I use Carthage. What should I do? Clone all 10 frameworks that I use and re-build them with a new Xcode which includes compiler 5.6? That may be a bad solution... Any answers on similar topics don't help..
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3.1k
Apr ’22
Actors with Combine publishers as properties.
Is it ok for an Actor type to have a Publisher as a property to let others observe changes over time? Or use the @Published property wrapper to achieve this? actor MyActor { var publisher = PassthroughSubject<Int, Never>() var data: Int { didSet { publisher.send(data) } } ... } // Usage var tasks = Set<AnyCancellable>() let actor = MyActor() Task { let publisher = await actor.publisher publisher.sink { print($0) }.store(in: &tasks) } This seems like this should be acceptable. I would expect a Publisher to be thread safe, and as long as the Output is a value type things should be fine. I have been getting random EXC_BAD_ACCESS errors when using this approach. But turning on the address sanitizer causes these crashes to go away. I know that isn't very specific but I wanted to start by seeing if this type of pattern is ok to do.
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2.8k
Sep ’22
Swift Decimal binary integer generic initializer fatal error
I am trying to use initialize a Decimal type using its generic binary integer exactly initializer but it keeps crashing with a fatal error regardless of the value used: Code to reproduce the issue: let binaryInteger = -10 let decimal = Decimal(exactly: binaryInteger) // error: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0). Is it a known bug?
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692
Oct ’22
Alternative to CoreTelephony for Accessing Cellular Network Information in Private iOS App
Hello, I am developing a private internal Flutter app for our customer, which will not be published on the Apple Store. One of the key features of this app is to collect RF strength metrics to share user experience with the network. For Android, we successfully implemented the required functionality and are able to collect the following metrics: Signal strength level (0-4) Signal strength in dBm RSSI RSRQ Cell ID Location Area Code Carrier name Mobile country code Mobile network code Radio access technology Connection status Duplex mode However, for iOS, we are facing challenges with CoreTelephony, which is not returning the necessary data. We are aware that CoreTelephony is deprecated and are looking for alternatives. We noticed that a lot of the information we need is available via FTMInternal-4. Is there a way to access this data for a private app? Are there any other recommended approaches or frameworks that can be used to gather cellular network information on iOS for an app that won't be distributed via the Apple Store? my swift code import Foundation import CoreTelephony class RfSignalStrengthImpl: RfSignalStrengthApi { func getCellularSignalStrength(completion: @escaping (Result<CellularSignalStrength, Error>) -> Void) { let networkInfo = CTTelephonyNetworkInfo() guard let carrier = networkInfo.serviceSubscriberCellularProviders?.values.first else { completion(.failure(NSError(domain: "com.xxxx.yyyy", code: 0, userInfo: [NSLocalizedDescriptionKey: "Carrier not found"]))) return } let carrierName = carrier.carrierName ?? "Unknown" let mobileCountryCode = carrier.mobileCountryCode ?? "Unknown" let mobileNetworkCode = carrier.mobileNetworkCode ?? "Unknown" let radioAccessTechnology = networkInfo.serviceCurrentRadioAccessTechnology?.values.first ?? "Unknown" var connectionStatus = "Unknown" ... ... } Thank you for your assistance.
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1.9k
May ’24
MPMediaItemPropertyArtwork crashes on Swift 6
Hey all! in my personal quest to make future proof apps moving to Swift 6, one of my app has a problem when setting an artwork image in MPNowPlayingInfoCenter Here's what I'm using to set the metadata func setMetadata(title: String? = nil, artist: String? = nil, artwork: String? = nil) async throws { let defaultArtwork = UIImage(named: "logo")! var nowPlayingInfo = [ MPMediaItemPropertyTitle: title ?? "***", MPMediaItemPropertyArtist: artist ?? "***", MPMediaItemPropertyArtwork: MPMediaItemArtwork(boundsSize: defaultArtwork.size) { _ in defaultArtwork } ] as [String: Any] if let artwork = artwork { guard let url = URL(string: artwork) else { return } let (data, response) = try await URLSession.shared.data(from: url) guard (response as? HTTPURLResponse)?.statusCode == 200 else { return } guard let image = UIImage(data: data) else { return } nowPlayingInfo[MPMediaItemPropertyArtwork] = MPMediaItemArtwork(boundsSize: image.size) { _ in image } } MPNowPlayingInfoCenter.default().nowPlayingInfo = nowPlayingInfo } the app crashes when hitting MPMediaItemPropertyArtwork: MPMediaItemArtwork(boundsSize: defaultArtwork.size) { _ in defaultArtwork } or nowPlayingInfo[MPMediaItemPropertyArtwork] = MPMediaItemArtwork(boundsSize: image.size) { _ in image } commenting out these two make the app work again. Again, no clue on why. Thanks in advance
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3.1k
Sep ’24
Crash with Progress type, Swift 6, iOS 18
We are getting a crash _dispatch_assert_queue_fail when the cancellationHandler on NSProgress is called. We do not see this with iOS 17.x, only on iOS 18. We are building in Swift 6 language mode and do not have any compiler warnings. We have a type whose init looks something like this: init( request: URLRequest, destinationURL: URL, session: URLSession ) { progress = Progress() progress.kind = .file progress.fileOperationKind = .downloading progress.fileURL = destinationURL progress.pausingHandler = { [weak self] in self?.setIsPaused(true) } progress.resumingHandler = { [weak self] in self?.setIsPaused(false) } progress.cancellationHandler = { [weak self] in self?.cancel() } When the progress is cancelled, and the cancellation handler is invoked. We get the crash. The crash is not reproducible 100% of the time, but it happens significantly often. Especially after cleaning and rebuilding and running our tests. * thread #4, queue = 'com.apple.root.default-qos', stop reason = EXC_BREAKPOINT (code=1, subcode=0x18017b0e8) * frame #0: 0x000000018017b0e8 libdispatch.dylib`_dispatch_assert_queue_fail + 116 frame #1: 0x000000018017b074 libdispatch.dylib`dispatch_assert_queue + 188 frame #2: 0x00000002444c63e0 libswift_Concurrency.dylib`swift_task_isCurrentExecutorImpl(swift::SerialExecutorRef) + 284 frame #3: 0x000000010b80bd84 MyTests`closure #3 in MyController.init() at MyController.swift:0 frame #4: 0x000000010b80bb04 MyTests`thunk for @escaping @callee_guaranteed @Sendable () -&gt; () at &lt;compiler-generated&gt;:0 frame #5: 0x00000001810276b0 Foundation`__20-[NSProgress cancel]_block_invoke_3 + 28 frame #6: 0x00000001801774ec libdispatch.dylib`_dispatch_call_block_and_release + 24 frame #7: 0x0000000180178de0 libdispatch.dylib`_dispatch_client_callout + 16 frame #8: 0x000000018018b7dc libdispatch.dylib`_dispatch_root_queue_drain + 1072 frame #9: 0x000000018018bf60 libdispatch.dylib`_dispatch_worker_thread2 + 232 frame #10: 0x00000001012a77d8 libsystem_pthread.dylib`_pthread_wqthread + 224 Any thoughts on why this is crashing and what we can do to work-around it? I have not been able to extract our code into a simple reproducible case yet. And I mostly see it when running our code in a testing environment (XCTest). Although I have been able to reproduce it running an app a few times, it's just less common.
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3.2k
Oct ’24
Type ReferenceWritableKeyPath does not conform to the 'Sendable' protocol
This is not a question but more of a hint where I was having trouble with. In my SwiftData App I wanted to move from Swift 5 to Swift 6, for that, as recommended, I stayed in Swift 5 language mode and set 'Strict Concurrency Checking' to 'Complete' within my build settings. It marked all the places where I was using predicates with the following warning: Type '' does not conform to the 'Sendable' protocol; this is an error in the Swift 6 language mode I had the same warnings for SortDescriptors. I spend quite some time searching the web and wrapping my head around how to solve that issue to be able to move to Swift 6. In the end I found this existing issue in the repository of the Swift Language https://github.com/swiftlang/swift/issues/68943. It says that this is not a warning that should be seen by the developer and in fact when turning Swift 6 language mode on those issues are not marked as errors. So if anyone is encountering this when trying to fix all issues while staying in Swift 5 language mode, ignore those, fix the other issues and turn on Swift 6 language mode and hopefully they are gone.
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1.1k
Oct ’24
Swift Concurrency Proposal Index
Swift concurrency is an important part of my day-to-day job. I created the following document for an internal presentation, and I figured that it might be helpful for others. If you have questions or comments, put them in a new thread here on DevForums. Use the App & System Services > Processes & Concurrency topic area and tag it with both Swift and Concurrency. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Swift Concurrency Proposal Index This post summarises the Swift Evolution proposals that went into the Swift concurrency design. It covers the proposal that are implemented in Swift 6.2, plus a few additional ones that aren’t currently available. The focus is here is the Swift Evolution proposals. For general information about Swift concurrency, see the documentation referenced by Concurrency Resources. Early Days Some early high-level discussions of concurrency on Swift Evolution: Swift Concurrency Manifesto (Aug 2017) — Introduces async and await and actors, including the main actor. If you’re curious, you can read the Swift Evolution thread that introduced this. Swift Concurrency Roadmap (Oct 2020) — This extended the design to include Task, structured concurrency, and Objective-C interoperability. Each subsystem had its own pitch thread [Concurrency] Asynchronous functions [Concurrency] Structured concurrency [Concurrency] Actors & actor isolation [Concurrency] Interoperability with Objective-C Swift 6.0 The following Swift Evolution proposals form the basis of the Swift 6.0 concurrency design. SE-0176 Enforce Exclusive Access to Memory link: SE-0176 notes: This defines the “Law of Exclusivity”, a critical foundation for both serial and concurrent code. SE-0282 Clarify the Swift memory consistency model ⚛︎ link: SE-0282 notes: This defines Swift’s memory model, that is, the rules about what is and isn’t allowed when it comes to concurrent memory access. SE-0296 Async/await link: SE-0296 introduces: async functions, async, await SE-0297 Concurrency Interoperability with Objective-C link: SE-0297 notes: Specifies how Swift imports an Objective-C method with a completion handler as an async method. Explicitly allows @objc actors. SE-0298 Async/Await: Sequences link: SE-0298 introduces: AsyncSequence, for await syntax notes: This just defines the AsyncSequence protocol. For one concrete implementation of that protocol, see SE-0314. SE-0300 Continuations for interfacing async tasks with synchronous code link: SE-0300 introduces: CheckedContinuation, UnsafeContinuation notes: Use these to create an async function that wraps a legacy request-reply concurrency construct. SE-0302 Sendable and @Sendable closures link: SE-0302 introduces: Sendable, @Sendable closures, marker protocols SE-0304 Structured concurrency link: SE-0304, third-party commentary introduces: unstructured and structured concurrency, Task, cancellation, CancellationError, withTaskCancellationHandler(…), sleep(…), withTaskGroup(…), withThrowingTaskGroup(…) notes: For the async let syntax, see SE-0317. For more ways to sleep, see SE-0329 and SE-0374. For discarding task groups, see SE-0381. SE-0306 Actors link: SE-0306 introduces: actor syntax notes: For actor-isolated parameters and the nonisolated keyword, see SE-0313. For global actors, see SE-0316. For custom executors and the Actor protocol, see SE-0392. SE-0311 Task Local Values link: SE-0311 introduces: TaskLocal SE-0313 Improved control over actor isolation link: SE-0313 introduces: isolated parameters, nonisolated SE-0314 AsyncStream and AsyncThrowingStream link: SE-0314 introduces: AsyncStream, AsyncThrowingStream, onTermination notes: These are super helpful when you need to publish a legacy notification construct as an async stream. For a simpler API to create a stream, see SE-0388. SE-0316 Global actors link: SE-0316 introduces: GlobalActor, MainActor notes: This includes the @MainActor syntax for closures. SE-0317 async let bindings link: SE-0317 introduces: async let syntax SE-0323 Asynchronous Main Semantics link: SE-0323 SE-0327 On Actors and Initialization link: SE-0327 notes: For a proposal to allow access to non-sendable isolated state in a deinitialiser, see SE-0371. SE-0329 Clock, Instant, and Duration link: SE-0329 introduces: Clock, InstantProtocol, DurationProtocol, Duration, ContinuousClock, SuspendingClock notes: For another way to sleep, see SE-0374. SE-0331 Remove Sendable conformance from unsafe pointer types link: SE-0331 SE-0337 Incremental migration to concurrency checking link: SE-0337 introduces: @preconcurrency, explicit unavailability of Sendable notes: This introduces @preconcurrency on declarations, on imports, and on Sendable protocols. For @preconcurrency conformances, see SE-0423. SE-0338 Clarify the Execution of Non-Actor-Isolated Async Functions link: SE-0338 note: This change has caught a bunch of folks by surprise and there’s a discussion underway as to whether to adjust it. SE-0340 Unavailable From Async Attribute link: SE-0340 introduces: noasync availability kind SE-0343 Concurrency in Top-level Code link: SE-0343 notes: For how strict concurrency applies to global variables, see SE-0412. SE-0374 Add sleep(for:) to Clock link: SE-0374 notes: This builds on SE-0329. SE-0381 DiscardingTaskGroups link: SE-0381 introduces: DiscardingTaskGroup, ThrowingDiscardingTaskGroup notes: Use this for task groups that can run indefinitely, for example, a network server. SE-0388 Convenience Async[Throwing]Stream.makeStream methods link: SE-0388 notes: This builds on SE-0314. SE-0392 Custom Actor Executors link: SE-0392 introduces: Actor protocol, Executor, SerialExecutor, ExecutorJob, assumeIsolated(…) notes: For task executors, a closely related concept, see SE-0417. For custom isolation checking, see SE-0424. SE-0395 Observation link: SE-0395 introduces: Observation module, Observable notes: While this isn’t directly related to concurrency, it’s relationship to Combine, which is an important exising concurrency construct, means I’ve included it in this list. SE-0401 Remove Actor Isolation Inference caused by Property Wrappers link: SE-0401, third-party commentary availability: upcoming feature flag: DisableOutwardActorInference SE-0410 Low-Level Atomic Operations ⚛︎ link: SE-0410 introduces: Synchronization module, Atomic, AtomicLazyReference, WordPair SE-0411 Isolated default value expressions link: SE-0411, third-party commentary SE-0412 Strict concurrency for global variables link: SE-0412 introduces: nonisolated(unsafe) notes: While this is a proposal about globals, the introduction of nonisolated(unsafe) applies to “any form of storage”. SE-0414 Region based Isolation link: SE-0414, third-party commentary notes: To send parameters and results across isolation regions, see SE-0430. SE-0417 Task Executor Preference link: SE-0417, third-party commentary introduces: withTaskExecutorPreference(…), TaskExecutor, globalConcurrentExecutor notes: This is closely related to the custom actor executors defined in SE-0392. SE-0418 Inferring Sendable for methods and key path literals link: SE-0418, third-party commentary availability: upcoming feature flag: InferSendableFromCaptures notes: The methods part of this is for “partial and unapplied methods”. SE-0420 Inheritance of actor isolation link: SE-0420, third-party commentary introduces: #isolation, optional isolated parameters notes: This is what makes it possible to iterate over an async stream in an isolated async function. SE-0421 Generalize effect polymorphism for AsyncSequence and AsyncIteratorProtocol link: SE-0421, third-party commentary notes: Previously AsyncSequence used an experimental mechanism to support throwing and non-throwing sequences. This moves it off that. Instead, it uses an extra Failure generic parameter and typed throws to achieve the same result. This allows it to finally support a primary associated type. Yay! SE-0423 Dynamic actor isolation enforcement from non-strict-concurrency contexts link: SE-0423, third-party commentary introduces: @preconcurrency conformance notes: This adds a number of dynamic actor isolation checks (think assumeIsolated(…)) to close strict concurrency holes that arise when you interact with legacy code. SE-0424 Custom isolation checking for SerialExecutor link: SE-0424, third-party commentary introduces: checkIsolation() notes: This extends the custom actor executors introduced in SE-0392 to support isolation checking. SE-0430 sending parameter and result values link: SE-0430, third-party commentary introduces: sending notes: Adds the ability to send parameters and results between the isolation regions introduced by SE-0414. SE-0431 @isolated(any) Function Types link: SE-0431, third-party commentary, third-party commentary introduces: @isolated(any) attribute on function types, isolation property of functions values notes: This is laying the groundwork for SE-NNNN Closure isolation control. That, in turn, aims to bring the currently experimental @_inheritActorContext attribute into the language officially. SE-0433 Synchronous Mutual Exclusion Lock 🔒 link: SE-0433 introduces: Mutex SE-0434 Usability of global-actor-isolated types link: SE-0434, third-party commentary availability: upcoming feature flag: GlobalActorIsolatedTypesUsability notes: This loosen strict concurrency checking in a number of subtle ways. Swift 6.1 Swift 6.1 has the following additions. Vision: Improving the approachability of data-race safety link: vision SE-0442 Allow TaskGroup’s ChildTaskResult Type To Be Inferred link: SE-0442, third-party commentary notes: This represents a small quality of life improvement for withTaskGroup(…) and withThrowingTaskGroup(…). SE-0449 Allow nonisolated to prevent global actor inference link: SE-0449, third-party commentary notes: This is a straightforward extension to the number of places you can apply nonisolated. Swift 6.2 Xcode 26 beta has two new build settings: Approachable Concurrency enables the following feature flags: DisableOutwardActorInference, GlobalActorIsolatedTypesUsability, InferIsolatedConformances, InferSendableFromCaptures, and NonisolatedNonsendingByDefault. Default Actor Isolation controls SE-0466 Swift 6.2, still in beta, has the following additions. SE-0371 Isolated synchronous deinit link: SE-0371, third-party commentary introduces: isolated deinit notes: Allows a deinitialiser to access non-sendable isolated state, lifting a restriction imposed by SE-0327. SE-0457 Expose attosecond representation of Duration link: SE-0457 introduces: attoseconds, init(attoseconds:) SE-0461 Run nonisolated async functions on the caller’s actor by default link: SE-0461 availability: upcoming feature flag: NonisolatedNonsendingByDefault introduces: nonisolated(nonsending), @concurrent notes: This represents a significant change to how Swift handles actor isolation by default, and introduces syntax to override that default. SE-0462 Task Priority Escalation APIs link: SE-0462 introduces: withTaskPriorityEscalationHandler(…) notes: Code that uses structured concurrency benefits from priority boosts automatically. This proposal exposes APIs so that code using unstructured concurrency can do the same. SE-0463 Import Objective-C completion handler parameters as @Sendable link: SE-0463 notes: This is a welcome resolution to a source of much confusion. SE-0466 Control default actor isolation inference link: SE-0466, third-party commentary availability: not officially approved, but a de facto part of Swift 6.2 introduces: -default-isolation compiler flag notes: This is a major component of the above-mentioned vision document. SE-0468 Hashable conformance for Async(Throwing)Stream.Continuation link: SE-0468 notes: This is an obvious benefit when you’re juggling a bunch of different async streams. SE-0469 Task Naming link: SE-0469 introduces: name, init(name:…) SE-0470 Global-actor isolated conformances link: SE-0470 availability: upcoming feature flag: InferIsolatedConformances introduces: @SomeActor protocol conformance notes: This is particularly useful when you want to conform an @MainActor type to Equatable, Hashable, and so on. SE-0471 Improved Custom SerialExecutor isolation checking for Concurrency Runtime link: SE-0471 notes: This is a welcome extension to SE-0424. SE-0472 Starting tasks synchronously from caller context link: SE-0472 introduces: immediate[Detached](…), addImmediateTask[UnlessCancelled](…), notes: This introduces the concept of an immediate task, one that initially uses the calling execution context. This is one of those things where, when you need it, you really need it. But it’s hard to summary when you might need it, so you’ll just have to read the proposal (-: In Progress The proposals in this section didn’t make Swift 6.2. SE-0406 Backpressure support for AsyncStream link: SE-0406 availability: returned for revision notes: Currently AsyncStream has very limited buffering options. This was a proposal to improve that. This feature is still very much needed, but the outlook for this proposal is hazy. My best guess is that something like this will land first in the Swift Async Algorithms package. See this thread. SE-NNNN Closure isolation control link: SE-NNNN introduces: @inheritsIsolation availability: not yet approved notes: This aims to bring the currently experimental @_inheritActorContext attribute into the language officially. It’s not clear how this will play out given the changes in SE-0461. Revision History 2026-02-16 Added the Early Days section. 2026-01-07 Added another third-party commentary links. 2025-09-02 Updated for the upcoming release Swift 6.2. 2025-04-07 Updated for the release of Swift 6.1, including a number of things that are still in progress. 2024-11-09 First post.
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2.6k
Nov ’24
Capturing self instead of using self. in switch case in DispatchQueue causes compiler error
I have an @objC used for notification. kTag is an Int constant, fieldBeingEdited is an Int variable. The following code fails at compilation with error: Command CompileSwift failed with a nonzero exit code if I capture self (I edited code, to have minimal case) @objc func keyboardDone(_ sender : UIButton) { DispatchQueue.main.async { [self] () -> Void in switch fieldBeingEdited { case kTag : break default : break } } } If I explicitly use self, it compiles, even with self captured: @objc func keyboardDone(_ sender : UIButton) { DispatchQueue.main.async { [self] () -> Void in switch fieldBeingEdited { // <<-- no need for self here case self.kTag : break // <<-- self here default : break } } } This compiles as well: @objc func keyboardDone(_ sender : UIButton) { DispatchQueue.main.async { () -> Void in switch self.fieldBeingEdited { // <<-- no need for self here case self.kTag : break // <<-- self here default : break } } } Is it a compiler bug or am I missing something ?
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446
Mar ’25
Compiler - method linking issue.
Issue: During app execution, the intended method is not being called; instead, the method preceding (written above the intended method) is being executed. For Example: //In my case the ViewController class is at 3rd level of inheritance. class ViewController: UIViewController { func methodA() { print("methodA") } func methodB() { print("methodB") } } let vc = ViewController() vc.methodB() Output: //"methodA" Expected: //"methodB" Observations: Recent code changes have revealed that enabling the below Swift-6 flag leads to this linking issue. When this flag is commented out, the problem disappears. .enableUpcomingFeature("InternalImportsByDefault") Additionally, moving the intended method into an extension of the same class resolves the issue when the flag is enabled. Conclusion: To resolve the issue: Comment out the Swift-6 flag. Alternatively, move the method into an extension of the same class, which addresses the issue for this specific case. I had similar issue in other class where it crashes with message "method not found", but actually the method is there. When moving the method into an extension of same class resolve this issue. Any help is much appreciated. Thanking you..
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175
Apr ’25
Calling StoreKit Swift from C++
What is the most obvious method of calling StoreKit from C++. I'm getting blocked by the fact that most of the critical StoreKit calls are async and functions marked a sync don't show up in the swift header for me to call from C++ (at least as far as I can tell). I'm trying to call let result = try await Product.products(for:productIDs) or let result = try await product.purchase() And C++ can't even see any functions I wrap these in as far as I can tell because i have to make them async. What am I missing? I tried a lot of alternates, like wrapping in Task { let result = try await Product.products(for:productIDs) } and it gives me 'Passing closure as a sending parameter' errors. Also when I try to call the same above code it gives me 'initializtion of immutable value never used' errors and the variables never appear. Code: struct storeChooser { public var productIDs: [String] public function checkProduct1 { Task { let result = try await Product.products(for: productIDs) } The above gives the initialization of immutable value skipped, and when I create a @State var products Then I get the 'passing closure as a sending parameter' error when i try to run it in a task it appears if I could make the function async and call it from C++ and have it return nothing it may work, does anyone know how to get C++ to see an async function in the -Swift.h file?
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195
May ’25
Swift / C++ Interop with Storekit - actor isolated structure cannot be exported to C++
I can't find a viable path to call StoreKit from C++ right now and would love some ideas. I'm implementing the code exactly as shown at 4:09 in https://developer.apple.com/videos/play/wwdc2023/10172/ However when I add any StoreKit functionality in I immediately get "Actor isolated structure cannot be exposed in C++" This makes me think I can't create a StoreKit view and call it from C++? Am I missing a better way? I don't think I can have another structure that holds the storeChooser in it because it will have the same problem (I assume, although I will check). Part of the issue seems to be that my app is C++ so there is no main function called in the swift for me to open this view with either, I was going to use the present function Zoe described (as below). I've tried a lot of alternative approaches but it seems to be blocking async functions from showing in C++ as well. So I'm not sure how to access the basic product(for:) and purchase(product) functions. import Foundation import StoreKit import SwiftUI public struct storeChooser: View { public var productIDs: [String] public var fetchError: String //@State //Note this is from the UI @State public var products: [Product] = [] // @State private var isPresented = true // weak private var host: UIViewController? = nil public init() { productIDs = ["20_super_crystals_v1"] products = [] self.fetchError = "untried" } public var body: some View { VStack(spacing: 20) { Text( "Products") ForEach(self.products) { product in Button { //dont do anything yet } label: { Text("\(product.displayPrice) - \(product.displayName)") } } }.task { do { try await self.loadProducts() } catch { print(error) } } } public func queryProducts() { Task { do { try await self.loadProducts() } catch { print(error) } } } public func getProduct1Name() -> String { if self.products.count > 0 { return self.products[0].displayName } else { return "empty" } } private func loadProducts() async throws { self.products = try await Product.products(for: self.productIDs) } /* public mutating func present(_ viewController: UIViewController) { isPresented = true; let host = UIHostingController(rootView: self) host.rootView.host = host viewController.present(host, animated: true) } */ }
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160
May ’25
Open any Swift view from C++
I've narrowed down my question after many rabbit holes - how can C++ code open any view in Swift. I can call functions in swift from C++ (works great), but not async or main actor (or actor at all) functions. And if I'm not mistaken all views are actors if not main actors? When calling from C+ I think its necessary that the first view be the main actor? I've implemented the code from the WWDC23 C++ interop video (Zoe's image picker) where I made a view in a struct, and just want to call it and let the view do the work. The compiler immediately gives me 'cannot expose main actors to C++'. If I'm not mistaken, doesn't this block the opening of any kind of swift view from C++? Hopefully I'm missing something obvious, which is likely :) In Zoe's code was his entry point into the program still Swift and not actually C++ app? Thanks! Thanks!
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162
May ’25
'init(coordinateRegion:interactionModes:showsUserLocation:userTrackingMode:annotationItems:annotationContent:)' was deprecated in iOS 17.0: Use Map initializers that t
I am currently encountering two deprecated errors in my code. Could someone please identify the issues with the code? Errors: 'init(coordinateRegion:interactionModes:showsUserLocation:userTrackingMode:annotationItems:annotationContent:)' was deprecated in iOS 17.0: Use Map initializers that take a MapContentBuilder instead. 'MapAnnotation' was deprecated in iOS 17.0: Use Annotation along with Map initializers that take a MapContentBuilder instead. Code: // MARK: - Stores Map (Dynamic) struct StoresMapView: View { @State private var storeLocations: [StoreLocation] = [] @State private var region = MKCoordinateRegion( center: CLLocationCoordinate2D(latitude: -31.95, longitude: 115.86), span: MKCoordinateSpan(latitudeDelta: 0.5, longitudeDelta: 0.5) ) var body: some View { Map(coordinateRegion: $region, interactionModes: .all, annotationItems: storeLocations) { store in MapAnnotation(coordinate: CLLocationCoordinate2D(latitude: store.latitude, longitude: store.longitude)) { VStack(spacing: 4) { Image(systemName: "leaf.circle.fill") .font(.title) .foregroundColor(.green) Text(store.name) .font(.caption) .fixedSize() } } } .onAppear(perform: loadStoreData) .navigationTitle("Store Locator") } private func loadStoreData() { guard let url = URL(string: "https://example.com/cop092/StoreLocations.json") else { return } URLSession.shared.dataTask(with: url) { data, _, _ in if let data = data, let decoded = try? JSONDecoder().decode([StoreLocation].self, from: data) { DispatchQueue.main.async { self.storeLocations = decoded if let first = decoded.first { self.region.center = CLLocationCoordinate2D(latitude: first.latitude, longitude: first.longitude) } } } }.resume() } }
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May ’25
swift_asyncLet_begin crashed
Crashed: com.apple.root.user-initiated-qos.cooperative 0 libswift_Concurrency.dylib 0x67f40 swift_task_create_commonImpl(unsigned long, swift::TaskOptionRecord*, swift::TargetMetadataswift::InProcess const*, void (swift::AsyncContext* swift_async_context) swiftasynccall*, void*, unsigned long) + 528 1 libswift_Concurrency.dylib 0x64d78 swift_asyncLet_begin + 40 2 AAAA 0x47aef28 (1) suspend resume partial function for ActivityContextModule.fetchRecord(startDate:endDate:) + 50786796 3 libswift_Concurrency.dylib 0x60f5c swift::runJobInEstablishedExecutorContext(swift::Job*) + 252 4 libswift_Concurrency.dylib 0x62514 swift_job_runImpl(swift::Job*, swift::SerialExecutorRef) + 144 5 libdispatch.dylib 0x15ec0 _dispatch_root_queue_drain + 392 6 libdispatch.dylib 0x166c4 _dispatch_worker_thread2 + 156 7 libsystem_pthread.dylib 0x3644 _pthread_wqthread + 228 8 libsystem_pthread.dylib 0x1474 start_wqthread + 8
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May ’25
Best practice: Use of enum without cases for static helper functions?
Hi all, In Swift, I often see static helper functions grouped in an enum without any cases, like this: enum StringUtils { static func camelCaseToSnakeCase(_ input: String) -> String { // implementation } } Since this enum has no cases, it cannot be instantiated – which is exactly the point. It’s meant to group related functionality without any stored state, and without the need for instantiation. This pattern avoids writing a struct with a private init() and makes the intent clearer: "This is just a static utility, not an object." You’ll often see this used for things like: AnalyticsEvents.track(_:) My question: Is this use of a case-less enum considered good practice in Swift when building static-only helpers? Or is there a better alternative for expressing intent and preventing instantiation? I’d appreciate any insight – especially if there’s official guidance or references from the Swift core team. Thanks!
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May ’25
Programming Languages Resources
This topic area is about the programming languages themselves, not about any specific API or tool. If you have an API question, go to the top level and look for a subtopic for that API. If you have a question about Apple developer tools, start in the Developer Tools & Services topic. For Swift questions: If your question is about the SwiftUI framework, start in UI Frameworks > SwiftUI. If your question is specific to the Swift Playground app, ask over in Developer Tools & Services > Swift Playground If you’re interested in the Swift open source effort — that includes the evolution of the language, the open source tools and libraries, and Swift on non-Apple platforms — check out Swift Forums If your question is about the Swift language, that’s on topic for Programming Languages > Swift, but you might have more luck asking it in Swift Forums > Using Swift. General: Forums topic: Programming Languages Swift: Forums subtopic: Programming Languages > Swift Forums tags: Swift Developer > Swift website Swift Programming Language website The Swift Programming Language documentation Swift Forums website, and specifically Swift Forums > Using Swift Swift Package Index website Concurrency Resources, which covers Swift concurrency How to think properly about binding memory Swift Forums thread Other: Forums subtopic: Programming Languages > Generic Forums tags: Objective-C Programming with Objective-C archived documentation Objective-C Runtime documentation Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"
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Oct ’25
Bridging Headers is unsupported or Module compiled with Swift 5.5.1 cannot be imported by the Swift 5.6 complier
Hello guys! I faced a problem with building... My device suddenly updated to iOS 15.4.1, my Xcode was 13.2 and I had to update it to the latest version (13.3.1) to build the app. After the update, I had a few problems which were successfully solved but one of them stopped me for a few hours. The problem is with Bridging Headers or Swift Compiler, I really don't know what I did badly, and what causes problems. On several forums I often read that is important to set: Build Settings &gt; Build Options &gt; Build Libraries for Distribution But in any case it doesn't work, on yes: error: using bridging headers with module interfaces is unsupported on no: (line with import framework SWXMLHash) /Users/blablabla/SSLModel.swift:9:8: error: module compiled with Swift 5.5.1 cannot be imported by the Swift 5.6 compiler: /Users/blablabla2/Build/Products/Debug-iphoneos/SWXMLHash.framework/Modules/SWXMLHash.swiftmodule/arm64-apple-ios.swiftmodule import SWXMLHash It will be important that I use Carthage. What should I do? Clone all 10 frameworks that I use and re-build them with a new Xcode which includes compiler 5.6? That may be a bad solution... Any answers on similar topics don't help..
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3.1k
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Apr ’22
Actors with Combine publishers as properties.
Is it ok for an Actor type to have a Publisher as a property to let others observe changes over time? Or use the @Published property wrapper to achieve this? actor MyActor { var publisher = PassthroughSubject<Int, Never>() var data: Int { didSet { publisher.send(data) } } ... } // Usage var tasks = Set<AnyCancellable>() let actor = MyActor() Task { let publisher = await actor.publisher publisher.sink { print($0) }.store(in: &tasks) } This seems like this should be acceptable. I would expect a Publisher to be thread safe, and as long as the Output is a value type things should be fine. I have been getting random EXC_BAD_ACCESS errors when using this approach. But turning on the address sanitizer causes these crashes to go away. I know that isn't very specific but I wanted to start by seeing if this type of pattern is ok to do.
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Sep ’22
Swift Decimal binary integer generic initializer fatal error
I am trying to use initialize a Decimal type using its generic binary integer exactly initializer but it keeps crashing with a fatal error regardless of the value used: Code to reproduce the issue: let binaryInteger = -10 let decimal = Decimal(exactly: binaryInteger) // error: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0). Is it a known bug?
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692
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Oct ’22
Alternative to CoreTelephony for Accessing Cellular Network Information in Private iOS App
Hello, I am developing a private internal Flutter app for our customer, which will not be published on the Apple Store. One of the key features of this app is to collect RF strength metrics to share user experience with the network. For Android, we successfully implemented the required functionality and are able to collect the following metrics: Signal strength level (0-4) Signal strength in dBm RSSI RSRQ Cell ID Location Area Code Carrier name Mobile country code Mobile network code Radio access technology Connection status Duplex mode However, for iOS, we are facing challenges with CoreTelephony, which is not returning the necessary data. We are aware that CoreTelephony is deprecated and are looking for alternatives. We noticed that a lot of the information we need is available via FTMInternal-4. Is there a way to access this data for a private app? Are there any other recommended approaches or frameworks that can be used to gather cellular network information on iOS for an app that won't be distributed via the Apple Store? my swift code import Foundation import CoreTelephony class RfSignalStrengthImpl: RfSignalStrengthApi { func getCellularSignalStrength(completion: @escaping (Result<CellularSignalStrength, Error>) -> Void) { let networkInfo = CTTelephonyNetworkInfo() guard let carrier = networkInfo.serviceSubscriberCellularProviders?.values.first else { completion(.failure(NSError(domain: "com.xxxx.yyyy", code: 0, userInfo: [NSLocalizedDescriptionKey: "Carrier not found"]))) return } let carrierName = carrier.carrierName ?? "Unknown" let mobileCountryCode = carrier.mobileCountryCode ?? "Unknown" let mobileNetworkCode = carrier.mobileNetworkCode ?? "Unknown" let radioAccessTechnology = networkInfo.serviceCurrentRadioAccessTechnology?.values.first ?? "Unknown" var connectionStatus = "Unknown" ... ... } Thank you for your assistance.
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May ’24
Swift Testing deinit not supporting async
Why doesn’t deinit support async? At the end of a test, I want to wipe data from HealthKit, and it’s delete function is asynchronous.
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Jul ’24
MPMediaItemPropertyArtwork crashes on Swift 6
Hey all! in my personal quest to make future proof apps moving to Swift 6, one of my app has a problem when setting an artwork image in MPNowPlayingInfoCenter Here's what I'm using to set the metadata func setMetadata(title: String? = nil, artist: String? = nil, artwork: String? = nil) async throws { let defaultArtwork = UIImage(named: "logo")! var nowPlayingInfo = [ MPMediaItemPropertyTitle: title ?? "***", MPMediaItemPropertyArtist: artist ?? "***", MPMediaItemPropertyArtwork: MPMediaItemArtwork(boundsSize: defaultArtwork.size) { _ in defaultArtwork } ] as [String: Any] if let artwork = artwork { guard let url = URL(string: artwork) else { return } let (data, response) = try await URLSession.shared.data(from: url) guard (response as? HTTPURLResponse)?.statusCode == 200 else { return } guard let image = UIImage(data: data) else { return } nowPlayingInfo[MPMediaItemPropertyArtwork] = MPMediaItemArtwork(boundsSize: image.size) { _ in image } } MPNowPlayingInfoCenter.default().nowPlayingInfo = nowPlayingInfo } the app crashes when hitting MPMediaItemPropertyArtwork: MPMediaItemArtwork(boundsSize: defaultArtwork.size) { _ in defaultArtwork } or nowPlayingInfo[MPMediaItemPropertyArtwork] = MPMediaItemArtwork(boundsSize: image.size) { _ in image } commenting out these two make the app work again. Again, no clue on why. Thanks in advance
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Sep ’24
Crash with Progress type, Swift 6, iOS 18
We are getting a crash _dispatch_assert_queue_fail when the cancellationHandler on NSProgress is called. We do not see this with iOS 17.x, only on iOS 18. We are building in Swift 6 language mode and do not have any compiler warnings. We have a type whose init looks something like this: init( request: URLRequest, destinationURL: URL, session: URLSession ) { progress = Progress() progress.kind = .file progress.fileOperationKind = .downloading progress.fileURL = destinationURL progress.pausingHandler = { [weak self] in self?.setIsPaused(true) } progress.resumingHandler = { [weak self] in self?.setIsPaused(false) } progress.cancellationHandler = { [weak self] in self?.cancel() } When the progress is cancelled, and the cancellation handler is invoked. We get the crash. The crash is not reproducible 100% of the time, but it happens significantly often. Especially after cleaning and rebuilding and running our tests. * thread #4, queue = 'com.apple.root.default-qos', stop reason = EXC_BREAKPOINT (code=1, subcode=0x18017b0e8) * frame #0: 0x000000018017b0e8 libdispatch.dylib`_dispatch_assert_queue_fail + 116 frame #1: 0x000000018017b074 libdispatch.dylib`dispatch_assert_queue + 188 frame #2: 0x00000002444c63e0 libswift_Concurrency.dylib`swift_task_isCurrentExecutorImpl(swift::SerialExecutorRef) + 284 frame #3: 0x000000010b80bd84 MyTests`closure #3 in MyController.init() at MyController.swift:0 frame #4: 0x000000010b80bb04 MyTests`thunk for @escaping @callee_guaranteed @Sendable () -&gt; () at &lt;compiler-generated&gt;:0 frame #5: 0x00000001810276b0 Foundation`__20-[NSProgress cancel]_block_invoke_3 + 28 frame #6: 0x00000001801774ec libdispatch.dylib`_dispatch_call_block_and_release + 24 frame #7: 0x0000000180178de0 libdispatch.dylib`_dispatch_client_callout + 16 frame #8: 0x000000018018b7dc libdispatch.dylib`_dispatch_root_queue_drain + 1072 frame #9: 0x000000018018bf60 libdispatch.dylib`_dispatch_worker_thread2 + 232 frame #10: 0x00000001012a77d8 libsystem_pthread.dylib`_pthread_wqthread + 224 Any thoughts on why this is crashing and what we can do to work-around it? I have not been able to extract our code into a simple reproducible case yet. And I mostly see it when running our code in a testing environment (XCTest). Although I have been able to reproduce it running an app a few times, it's just less common.
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Oct ’24
Type ReferenceWritableKeyPath does not conform to the 'Sendable' protocol
This is not a question but more of a hint where I was having trouble with. In my SwiftData App I wanted to move from Swift 5 to Swift 6, for that, as recommended, I stayed in Swift 5 language mode and set 'Strict Concurrency Checking' to 'Complete' within my build settings. It marked all the places where I was using predicates with the following warning: Type '' does not conform to the 'Sendable' protocol; this is an error in the Swift 6 language mode I had the same warnings for SortDescriptors. I spend quite some time searching the web and wrapping my head around how to solve that issue to be able to move to Swift 6. In the end I found this existing issue in the repository of the Swift Language https://github.com/swiftlang/swift/issues/68943. It says that this is not a warning that should be seen by the developer and in fact when turning Swift 6 language mode on those issues are not marked as errors. So if anyone is encountering this when trying to fix all issues while staying in Swift 5 language mode, ignore those, fix the other issues and turn on Swift 6 language mode and hopefully they are gone.
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Oct ’24
Swift Concurrency Proposal Index
Swift concurrency is an important part of my day-to-day job. I created the following document for an internal presentation, and I figured that it might be helpful for others. If you have questions or comments, put them in a new thread here on DevForums. Use the App & System Services > Processes & Concurrency topic area and tag it with both Swift and Concurrency. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Swift Concurrency Proposal Index This post summarises the Swift Evolution proposals that went into the Swift concurrency design. It covers the proposal that are implemented in Swift 6.2, plus a few additional ones that aren’t currently available. The focus is here is the Swift Evolution proposals. For general information about Swift concurrency, see the documentation referenced by Concurrency Resources. Early Days Some early high-level discussions of concurrency on Swift Evolution: Swift Concurrency Manifesto (Aug 2017) — Introduces async and await and actors, including the main actor. If you’re curious, you can read the Swift Evolution thread that introduced this. Swift Concurrency Roadmap (Oct 2020) — This extended the design to include Task, structured concurrency, and Objective-C interoperability. Each subsystem had its own pitch thread [Concurrency] Asynchronous functions [Concurrency] Structured concurrency [Concurrency] Actors & actor isolation [Concurrency] Interoperability with Objective-C Swift 6.0 The following Swift Evolution proposals form the basis of the Swift 6.0 concurrency design. SE-0176 Enforce Exclusive Access to Memory link: SE-0176 notes: This defines the “Law of Exclusivity”, a critical foundation for both serial and concurrent code. SE-0282 Clarify the Swift memory consistency model ⚛︎ link: SE-0282 notes: This defines Swift’s memory model, that is, the rules about what is and isn’t allowed when it comes to concurrent memory access. SE-0296 Async/await link: SE-0296 introduces: async functions, async, await SE-0297 Concurrency Interoperability with Objective-C link: SE-0297 notes: Specifies how Swift imports an Objective-C method with a completion handler as an async method. Explicitly allows @objc actors. SE-0298 Async/Await: Sequences link: SE-0298 introduces: AsyncSequence, for await syntax notes: This just defines the AsyncSequence protocol. For one concrete implementation of that protocol, see SE-0314. SE-0300 Continuations for interfacing async tasks with synchronous code link: SE-0300 introduces: CheckedContinuation, UnsafeContinuation notes: Use these to create an async function that wraps a legacy request-reply concurrency construct. SE-0302 Sendable and @Sendable closures link: SE-0302 introduces: Sendable, @Sendable closures, marker protocols SE-0304 Structured concurrency link: SE-0304, third-party commentary introduces: unstructured and structured concurrency, Task, cancellation, CancellationError, withTaskCancellationHandler(…), sleep(…), withTaskGroup(…), withThrowingTaskGroup(…) notes: For the async let syntax, see SE-0317. For more ways to sleep, see SE-0329 and SE-0374. For discarding task groups, see SE-0381. SE-0306 Actors link: SE-0306 introduces: actor syntax notes: For actor-isolated parameters and the nonisolated keyword, see SE-0313. For global actors, see SE-0316. For custom executors and the Actor protocol, see SE-0392. SE-0311 Task Local Values link: SE-0311 introduces: TaskLocal SE-0313 Improved control over actor isolation link: SE-0313 introduces: isolated parameters, nonisolated SE-0314 AsyncStream and AsyncThrowingStream link: SE-0314 introduces: AsyncStream, AsyncThrowingStream, onTermination notes: These are super helpful when you need to publish a legacy notification construct as an async stream. For a simpler API to create a stream, see SE-0388. SE-0316 Global actors link: SE-0316 introduces: GlobalActor, MainActor notes: This includes the @MainActor syntax for closures. SE-0317 async let bindings link: SE-0317 introduces: async let syntax SE-0323 Asynchronous Main Semantics link: SE-0323 SE-0327 On Actors and Initialization link: SE-0327 notes: For a proposal to allow access to non-sendable isolated state in a deinitialiser, see SE-0371. SE-0329 Clock, Instant, and Duration link: SE-0329 introduces: Clock, InstantProtocol, DurationProtocol, Duration, ContinuousClock, SuspendingClock notes: For another way to sleep, see SE-0374. SE-0331 Remove Sendable conformance from unsafe pointer types link: SE-0331 SE-0337 Incremental migration to concurrency checking link: SE-0337 introduces: @preconcurrency, explicit unavailability of Sendable notes: This introduces @preconcurrency on declarations, on imports, and on Sendable protocols. For @preconcurrency conformances, see SE-0423. SE-0338 Clarify the Execution of Non-Actor-Isolated Async Functions link: SE-0338 note: This change has caught a bunch of folks by surprise and there’s a discussion underway as to whether to adjust it. SE-0340 Unavailable From Async Attribute link: SE-0340 introduces: noasync availability kind SE-0343 Concurrency in Top-level Code link: SE-0343 notes: For how strict concurrency applies to global variables, see SE-0412. SE-0374 Add sleep(for:) to Clock link: SE-0374 notes: This builds on SE-0329. SE-0381 DiscardingTaskGroups link: SE-0381 introduces: DiscardingTaskGroup, ThrowingDiscardingTaskGroup notes: Use this for task groups that can run indefinitely, for example, a network server. SE-0388 Convenience Async[Throwing]Stream.makeStream methods link: SE-0388 notes: This builds on SE-0314. SE-0392 Custom Actor Executors link: SE-0392 introduces: Actor protocol, Executor, SerialExecutor, ExecutorJob, assumeIsolated(…) notes: For task executors, a closely related concept, see SE-0417. For custom isolation checking, see SE-0424. SE-0395 Observation link: SE-0395 introduces: Observation module, Observable notes: While this isn’t directly related to concurrency, it’s relationship to Combine, which is an important exising concurrency construct, means I’ve included it in this list. SE-0401 Remove Actor Isolation Inference caused by Property Wrappers link: SE-0401, third-party commentary availability: upcoming feature flag: DisableOutwardActorInference SE-0410 Low-Level Atomic Operations ⚛︎ link: SE-0410 introduces: Synchronization module, Atomic, AtomicLazyReference, WordPair SE-0411 Isolated default value expressions link: SE-0411, third-party commentary SE-0412 Strict concurrency for global variables link: SE-0412 introduces: nonisolated(unsafe) notes: While this is a proposal about globals, the introduction of nonisolated(unsafe) applies to “any form of storage”. SE-0414 Region based Isolation link: SE-0414, third-party commentary notes: To send parameters and results across isolation regions, see SE-0430. SE-0417 Task Executor Preference link: SE-0417, third-party commentary introduces: withTaskExecutorPreference(…), TaskExecutor, globalConcurrentExecutor notes: This is closely related to the custom actor executors defined in SE-0392. SE-0418 Inferring Sendable for methods and key path literals link: SE-0418, third-party commentary availability: upcoming feature flag: InferSendableFromCaptures notes: The methods part of this is for “partial and unapplied methods”. SE-0420 Inheritance of actor isolation link: SE-0420, third-party commentary introduces: #isolation, optional isolated parameters notes: This is what makes it possible to iterate over an async stream in an isolated async function. SE-0421 Generalize effect polymorphism for AsyncSequence and AsyncIteratorProtocol link: SE-0421, third-party commentary notes: Previously AsyncSequence used an experimental mechanism to support throwing and non-throwing sequences. This moves it off that. Instead, it uses an extra Failure generic parameter and typed throws to achieve the same result. This allows it to finally support a primary associated type. Yay! SE-0423 Dynamic actor isolation enforcement from non-strict-concurrency contexts link: SE-0423, third-party commentary introduces: @preconcurrency conformance notes: This adds a number of dynamic actor isolation checks (think assumeIsolated(…)) to close strict concurrency holes that arise when you interact with legacy code. SE-0424 Custom isolation checking for SerialExecutor link: SE-0424, third-party commentary introduces: checkIsolation() notes: This extends the custom actor executors introduced in SE-0392 to support isolation checking. SE-0430 sending parameter and result values link: SE-0430, third-party commentary introduces: sending notes: Adds the ability to send parameters and results between the isolation regions introduced by SE-0414. SE-0431 @isolated(any) Function Types link: SE-0431, third-party commentary, third-party commentary introduces: @isolated(any) attribute on function types, isolation property of functions values notes: This is laying the groundwork for SE-NNNN Closure isolation control. That, in turn, aims to bring the currently experimental @_inheritActorContext attribute into the language officially. SE-0433 Synchronous Mutual Exclusion Lock 🔒 link: SE-0433 introduces: Mutex SE-0434 Usability of global-actor-isolated types link: SE-0434, third-party commentary availability: upcoming feature flag: GlobalActorIsolatedTypesUsability notes: This loosen strict concurrency checking in a number of subtle ways. Swift 6.1 Swift 6.1 has the following additions. Vision: Improving the approachability of data-race safety link: vision SE-0442 Allow TaskGroup’s ChildTaskResult Type To Be Inferred link: SE-0442, third-party commentary notes: This represents a small quality of life improvement for withTaskGroup(…) and withThrowingTaskGroup(…). SE-0449 Allow nonisolated to prevent global actor inference link: SE-0449, third-party commentary notes: This is a straightforward extension to the number of places you can apply nonisolated. Swift 6.2 Xcode 26 beta has two new build settings: Approachable Concurrency enables the following feature flags: DisableOutwardActorInference, GlobalActorIsolatedTypesUsability, InferIsolatedConformances, InferSendableFromCaptures, and NonisolatedNonsendingByDefault. Default Actor Isolation controls SE-0466 Swift 6.2, still in beta, has the following additions. SE-0371 Isolated synchronous deinit link: SE-0371, third-party commentary introduces: isolated deinit notes: Allows a deinitialiser to access non-sendable isolated state, lifting a restriction imposed by SE-0327. SE-0457 Expose attosecond representation of Duration link: SE-0457 introduces: attoseconds, init(attoseconds:) SE-0461 Run nonisolated async functions on the caller’s actor by default link: SE-0461 availability: upcoming feature flag: NonisolatedNonsendingByDefault introduces: nonisolated(nonsending), @concurrent notes: This represents a significant change to how Swift handles actor isolation by default, and introduces syntax to override that default. SE-0462 Task Priority Escalation APIs link: SE-0462 introduces: withTaskPriorityEscalationHandler(…) notes: Code that uses structured concurrency benefits from priority boosts automatically. This proposal exposes APIs so that code using unstructured concurrency can do the same. SE-0463 Import Objective-C completion handler parameters as @Sendable link: SE-0463 notes: This is a welcome resolution to a source of much confusion. SE-0466 Control default actor isolation inference link: SE-0466, third-party commentary availability: not officially approved, but a de facto part of Swift 6.2 introduces: -default-isolation compiler flag notes: This is a major component of the above-mentioned vision document. SE-0468 Hashable conformance for Async(Throwing)Stream.Continuation link: SE-0468 notes: This is an obvious benefit when you’re juggling a bunch of different async streams. SE-0469 Task Naming link: SE-0469 introduces: name, init(name:…) SE-0470 Global-actor isolated conformances link: SE-0470 availability: upcoming feature flag: InferIsolatedConformances introduces: @SomeActor protocol conformance notes: This is particularly useful when you want to conform an @MainActor type to Equatable, Hashable, and so on. SE-0471 Improved Custom SerialExecutor isolation checking for Concurrency Runtime link: SE-0471 notes: This is a welcome extension to SE-0424. SE-0472 Starting tasks synchronously from caller context link: SE-0472 introduces: immediate[Detached](…), addImmediateTask[UnlessCancelled](…), notes: This introduces the concept of an immediate task, one that initially uses the calling execution context. This is one of those things where, when you need it, you really need it. But it’s hard to summary when you might need it, so you’ll just have to read the proposal (-: In Progress The proposals in this section didn’t make Swift 6.2. SE-0406 Backpressure support for AsyncStream link: SE-0406 availability: returned for revision notes: Currently AsyncStream has very limited buffering options. This was a proposal to improve that. This feature is still very much needed, but the outlook for this proposal is hazy. My best guess is that something like this will land first in the Swift Async Algorithms package. See this thread. SE-NNNN Closure isolation control link: SE-NNNN introduces: @inheritsIsolation availability: not yet approved notes: This aims to bring the currently experimental @_inheritActorContext attribute into the language officially. It’s not clear how this will play out given the changes in SE-0461. Revision History 2026-02-16 Added the Early Days section. 2026-01-07 Added another third-party commentary links. 2025-09-02 Updated for the upcoming release Swift 6.2. 2025-04-07 Updated for the release of Swift 6.1, including a number of things that are still in progress. 2024-11-09 First post.
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Nov ’24
the compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions
"the compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions" ...... it killing me !!!!
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Dec ’24
Using .mp3 files in Swift Playgrounds project
Hello, I have an issue with importing some .mp3 files into a swift playground project (in Xcode, not in the Playground app). They worked fine in the Xcode project, but for some reason playgrounds isn't able to find them. I imported them the exact same way as I did in the Xcode project.
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Jan ’25
Capturing self instead of using self. in switch case in DispatchQueue causes compiler error
I have an @objC used for notification. kTag is an Int constant, fieldBeingEdited is an Int variable. The following code fails at compilation with error: Command CompileSwift failed with a nonzero exit code if I capture self (I edited code, to have minimal case) @objc func keyboardDone(_ sender : UIButton) { DispatchQueue.main.async { [self] () -> Void in switch fieldBeingEdited { case kTag : break default : break } } } If I explicitly use self, it compiles, even with self captured: @objc func keyboardDone(_ sender : UIButton) { DispatchQueue.main.async { [self] () -> Void in switch fieldBeingEdited { // <<-- no need for self here case self.kTag : break // <<-- self here default : break } } } This compiles as well: @objc func keyboardDone(_ sender : UIButton) { DispatchQueue.main.async { () -> Void in switch self.fieldBeingEdited { // <<-- no need for self here case self.kTag : break // <<-- self here default : break } } } Is it a compiler bug or am I missing something ?
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446
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Mar ’25
Swift question:
Is there a swift6 manual that will teach me how to code in swift?
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206
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Apr ’25
Compiler - method linking issue.
Issue: During app execution, the intended method is not being called; instead, the method preceding (written above the intended method) is being executed. For Example: //In my case the ViewController class is at 3rd level of inheritance. class ViewController: UIViewController { func methodA() { print("methodA") } func methodB() { print("methodB") } } let vc = ViewController() vc.methodB() Output: //"methodA" Expected: //"methodB" Observations: Recent code changes have revealed that enabling the below Swift-6 flag leads to this linking issue. When this flag is commented out, the problem disappears. .enableUpcomingFeature("InternalImportsByDefault") Additionally, moving the intended method into an extension of the same class resolves the issue when the flag is enabled. Conclusion: To resolve the issue: Comment out the Swift-6 flag. Alternatively, move the method into an extension of the same class, which addresses the issue for this specific case. I had similar issue in other class where it crashes with message "method not found", but actually the method is there. When moving the method into an extension of same class resolve this issue. Any help is much appreciated. Thanking you..
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175
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Apr ’25
Calling StoreKit Swift from C++
What is the most obvious method of calling StoreKit from C++. I'm getting blocked by the fact that most of the critical StoreKit calls are async and functions marked a sync don't show up in the swift header for me to call from C++ (at least as far as I can tell). I'm trying to call let result = try await Product.products(for:productIDs) or let result = try await product.purchase() And C++ can't even see any functions I wrap these in as far as I can tell because i have to make them async. What am I missing? I tried a lot of alternates, like wrapping in Task { let result = try await Product.products(for:productIDs) } and it gives me 'Passing closure as a sending parameter' errors. Also when I try to call the same above code it gives me 'initializtion of immutable value never used' errors and the variables never appear. Code: struct storeChooser { public var productIDs: [String] public function checkProduct1 { Task { let result = try await Product.products(for: productIDs) } The above gives the initialization of immutable value skipped, and when I create a @State var products Then I get the 'passing closure as a sending parameter' error when i try to run it in a task it appears if I could make the function async and call it from C++ and have it return nothing it may work, does anyone know how to get C++ to see an async function in the -Swift.h file?
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195
Activity
May ’25
Swift / C++ Interop with Storekit - actor isolated structure cannot be exported to C++
I can't find a viable path to call StoreKit from C++ right now and would love some ideas. I'm implementing the code exactly as shown at 4:09 in https://developer.apple.com/videos/play/wwdc2023/10172/ However when I add any StoreKit functionality in I immediately get "Actor isolated structure cannot be exposed in C++" This makes me think I can't create a StoreKit view and call it from C++? Am I missing a better way? I don't think I can have another structure that holds the storeChooser in it because it will have the same problem (I assume, although I will check). Part of the issue seems to be that my app is C++ so there is no main function called in the swift for me to open this view with either, I was going to use the present function Zoe described (as below). I've tried a lot of alternative approaches but it seems to be blocking async functions from showing in C++ as well. So I'm not sure how to access the basic product(for:) and purchase(product) functions. import Foundation import StoreKit import SwiftUI public struct storeChooser: View { public var productIDs: [String] public var fetchError: String //@State //Note this is from the UI @State public var products: [Product] = [] // @State private var isPresented = true // weak private var host: UIViewController? = nil public init() { productIDs = ["20_super_crystals_v1"] products = [] self.fetchError = "untried" } public var body: some View { VStack(spacing: 20) { Text( "Products") ForEach(self.products) { product in Button { //dont do anything yet } label: { Text("\(product.displayPrice) - \(product.displayName)") } } }.task { do { try await self.loadProducts() } catch { print(error) } } } public func queryProducts() { Task { do { try await self.loadProducts() } catch { print(error) } } } public func getProduct1Name() -> String { if self.products.count > 0 { return self.products[0].displayName } else { return "empty" } } private func loadProducts() async throws { self.products = try await Product.products(for: self.productIDs) } /* public mutating func present(_ viewController: UIViewController) { isPresented = true; let host = UIHostingController(rootView: self) host.rootView.host = host viewController.present(host, animated: true) } */ }
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160
Activity
May ’25
Open any Swift view from C++
I've narrowed down my question after many rabbit holes - how can C++ code open any view in Swift. I can call functions in swift from C++ (works great), but not async or main actor (or actor at all) functions. And if I'm not mistaken all views are actors if not main actors? When calling from C+ I think its necessary that the first view be the main actor? I've implemented the code from the WWDC23 C++ interop video (Zoe's image picker) where I made a view in a struct, and just want to call it and let the view do the work. The compiler immediately gives me 'cannot expose main actors to C++'. If I'm not mistaken, doesn't this block the opening of any kind of swift view from C++? Hopefully I'm missing something obvious, which is likely :) In Zoe's code was his entry point into the program still Swift and not actually C++ app? Thanks! Thanks!
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162
Activity
May ’25
'init(coordinateRegion:interactionModes:showsUserLocation:userTrackingMode:annotationItems:annotationContent:)' was deprecated in iOS 17.0: Use Map initializers that t
I am currently encountering two deprecated errors in my code. Could someone please identify the issues with the code? Errors: 'init(coordinateRegion:interactionModes:showsUserLocation:userTrackingMode:annotationItems:annotationContent:)' was deprecated in iOS 17.0: Use Map initializers that take a MapContentBuilder instead. 'MapAnnotation' was deprecated in iOS 17.0: Use Annotation along with Map initializers that take a MapContentBuilder instead. Code: // MARK: - Stores Map (Dynamic) struct StoresMapView: View { @State private var storeLocations: [StoreLocation] = [] @State private var region = MKCoordinateRegion( center: CLLocationCoordinate2D(latitude: -31.95, longitude: 115.86), span: MKCoordinateSpan(latitudeDelta: 0.5, longitudeDelta: 0.5) ) var body: some View { Map(coordinateRegion: $region, interactionModes: .all, annotationItems: storeLocations) { store in MapAnnotation(coordinate: CLLocationCoordinate2D(latitude: store.latitude, longitude: store.longitude)) { VStack(spacing: 4) { Image(systemName: "leaf.circle.fill") .font(.title) .foregroundColor(.green) Text(store.name) .font(.caption) .fixedSize() } } } .onAppear(perform: loadStoreData) .navigationTitle("Store Locator") } private func loadStoreData() { guard let url = URL(string: "https://example.com/cop092/StoreLocations.json") else { return } URLSession.shared.dataTask(with: url) { data, _, _ in if let data = data, let decoded = try? JSONDecoder().decode([StoreLocation].self, from: data) { DispatchQueue.main.async { self.storeLocations = decoded if let first = decoded.first { self.region.center = CLLocationCoordinate2D(latitude: first.latitude, longitude: first.longitude) } } } }.resume() } }
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187
Activity
May ’25
swift_asyncLet_begin crashed
Crashed: com.apple.root.user-initiated-qos.cooperative 0 libswift_Concurrency.dylib 0x67f40 swift_task_create_commonImpl(unsigned long, swift::TaskOptionRecord*, swift::TargetMetadataswift::InProcess const*, void (swift::AsyncContext* swift_async_context) swiftasynccall*, void*, unsigned long) + 528 1 libswift_Concurrency.dylib 0x64d78 swift_asyncLet_begin + 40 2 AAAA 0x47aef28 (1) suspend resume partial function for ActivityContextModule.fetchRecord(startDate:endDate:) + 50786796 3 libswift_Concurrency.dylib 0x60f5c swift::runJobInEstablishedExecutorContext(swift::Job*) + 252 4 libswift_Concurrency.dylib 0x62514 swift_job_runImpl(swift::Job*, swift::SerialExecutorRef) + 144 5 libdispatch.dylib 0x15ec0 _dispatch_root_queue_drain + 392 6 libdispatch.dylib 0x166c4 _dispatch_worker_thread2 + 156 7 libsystem_pthread.dylib 0x3644 _pthread_wqthread + 228 8 libsystem_pthread.dylib 0x1474 start_wqthread + 8
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193
Activity
May ’25
Best practice: Use of enum without cases for static helper functions?
Hi all, In Swift, I often see static helper functions grouped in an enum without any cases, like this: enum StringUtils { static func camelCaseToSnakeCase(_ input: String) -> String { // implementation } } Since this enum has no cases, it cannot be instantiated – which is exactly the point. It’s meant to group related functionality without any stored state, and without the need for instantiation. This pattern avoids writing a struct with a private init() and makes the intent clearer: "This is just a static utility, not an object." You’ll often see this used for things like: AnalyticsEvents.track(_:) My question: Is this use of a case-less enum considered good practice in Swift when building static-only helpers? Or is there a better alternative for expressing intent and preventing instantiation? I’d appreciate any insight – especially if there’s official guidance or references from the Swift core team. Thanks!
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222
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May ’25