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SwiftData document-based app crashes on undo/redo without ModelContext.transaction(block:)
Overview I'm developing a document-based app for macOS using SwiftData. When I undo/redo changes using Command-Z/Command-Shift-Z, the app reliably crashes with the following error: SwiftData/ModelSnapshot.swift:46: Fatal error: Unexpected backing data for snapshot creation: SwiftData._FullFutureBackingData<DocumentTest.ChildItem> And before the app crashes, what always happens is that UndoManager stops removing/restoring instances of ChildItem (but continues to remove/restore instances of ParentItem). The issue goes away when I enclose the relevant code in ModelContext.transaction(block:). However, this shouldn't be necessary, as ModelContext.autosaveEnabled is true by default. The issues are occurring with Xcode 26.4 (17E192) and macOS Tahoe 26.4 (25E246). I have modified the macOS Document App project template to showcase the issue. The sample project, along with a screen recording of the crash, can be downloaded from here: https://drive.google.com/drive/folders/13bCB1qRZ6273BI81zW2zUUBraSvv6p5w?usp=share_link Is this expected behavior or should I file a bug report in Feedback Assistant? Steps to Reproduce To recreate the issue, follow these steps: Download and extract the "Xcode Project.zip" file linked above. Open the extracted "DocumentTest" project in Xcode. Build and run the "DocumentTest" app. In the document selection window, click "New Document" at the bottom-left. In the app, click the "+" button at the top-right to add a ParentItem with ChildItems. Click on the added ParentItem's button to add another ChildItem to it. Repeat steps 5–6 until you have 5 ParentItems with an additional ChildItem. Press Command-Z 10 times to undo all the changes. Press Command-Shift-Z 10 times to redo all the changes. Repeat steps 8–9 until UndoManager stops removing/restoring the additional ChildItem, and continue repeating them until the app eventually crashes (you may have to repeat them 5–10 times before the issue occurs). If you uncomment the ModelContext.transaction(block:) at line 13 of ContentView.swift and repeat the same steps above, no ChildItems will go missing and the app will not crash. Code ParentItem Model @Model final class ParentItem { var timestamp: Date @Relationship( deleteRule: .cascade, inverse: \ChildItem.parentItem ) var childItems: [ChildItem] = [] init(timestamp: Date) { self.timestamp = timestamp } } ChildItem Model @Model final class ChildItem { var index: Int var parentItem: ParentItem? init(index: Int) { self.index = index } } Creating, Inserting, and Linking ParentItem and ChildItem // Create and insert ParentItem let newParentItem = ParentItem( timestamp: Date() ) modelContext.insert(newParentItem) // Create and insert ChildItems var newChildItems: [ChildItem] = [] for index in 0..<Int.random(in: 2...8) { let newChildItem = ChildItem(index: index) newChildItems.append(newChildItem) modelContext.insert(newChildItem) } /* Establish relationship between ParentItem and ChildItems */ for newChildItem in newChildItems { newParentItem.childItems.append( newChildItem ) newChildItem.parentItem = newParentItem } Adding an Additional ChildItem to ParentItem // Uncommenting this block fixes the crash // try! modelContext.transaction { // Create and insert the new ChildItem let newChildItem = ChildItem( index: parentItem.childItems.count ) modelContext.insert(newChildItem) // Establish relationship to parentItem parentItem.childItems.append(newChildItem) newChildItem.parentItem = parentItem // }
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SwiftData document-based app crashes on undo/redo without ModelContext.transaction(block:)
Overview I'm developing a document-based app for macOS using SwiftData. When I undo/redo changes using Command-Z/Command-Shift-Z, the app reliably crashes with the following error: SwiftData/ModelSnapshot.swift:46: Fatal error: Unexpected backing data for snapshot creation: SwiftData._FullFutureBackingData<DocumentTest.ChildItem> And before the app crashes, what always happens is that UndoManager stops removing/restoring instances of ChildItem (but continues to remove/restore instances of ParentItem). The issue goes away when I enclose the relevant code in ModelContext.transaction(block:). However, this shouldn't be necessary, as ModelContext.autosaveEnabled is true by default. The issues are occurring with Xcode 26.4 (17E192) and macOS Tahoe 26.4 (25E246). I have modified the macOS Document App project template to showcase the issue. The sample project, along with a screen recording of the crash, can be downloaded from here: https://drive.google.com/drive/folders/13bCB1qRZ6273BI81zW2zUUBraSvv6p5w?usp=share_link Is this expected behavior or should I file a bug report in Feedback Assistant? Steps to Reproduce To recreate the issue, follow these steps: Download and extract the "Xcode Project.zip" file linked above. Open the extracted "DocumentTest" project in Xcode. Build and run the "DocumentTest" app. In the document selection window, click "New Document" at the bottom-left. In the app, click the "+" button at the top-right to add a ParentItem with ChildItems. Click on the added ParentItem's button to add another ChildItem to it. Repeat steps 5–6 until you have 5 ParentItems with an additional ChildItem. Press Command-Z 10 times to undo all the changes. Press Command-Shift-Z 10 times to redo all the changes. Repeat steps 8–9 until UndoManager stops removing/restoring the additional ChildItem, and continue repeating them until the app eventually crashes (you may have to repeat them 5–10 times before the issue occurs). If you uncomment the ModelContext.transaction(block:) at line 13 of ContentView.swift and repeat the same steps above, no ChildItems will go missing and the app will not crash. Code ParentItem Model @Model final class ParentItem { var timestamp: Date @Relationship( deleteRule: .cascade, inverse: \ChildItem.parentItem ) var childItems: [ChildItem] = [] init(timestamp: Date) { self.timestamp = timestamp } } ChildItem Model @Model final class ChildItem { var index: Int var parentItem: ParentItem? init(index: Int) { self.index = index } } Creating, Inserting, and Linking ParentItem and ChildItem // Create and insert ParentItem let newParentItem = ParentItem( timestamp: Date() ) modelContext.insert(newParentItem) // Create and insert ChildItems var newChildItems: [ChildItem] = [] for index in 0..<Int.random(in: 2...8) { let newChildItem = ChildItem(index: index) newChildItems.append(newChildItem) modelContext.insert(newChildItem) } /* Establish relationship between ParentItem and ChildItems */ for newChildItem in newChildItems { newParentItem.childItems.append( newChildItem ) newChildItem.parentItem = newParentItem } Adding an Additional ChildItem to ParentItem // Uncommenting this block fixes the crash // try! modelContext.transaction { // Create and insert the new ChildItem let newChildItem = ChildItem( index: parentItem.childItems.count ) modelContext.insert(newChildItem) // Establish relationship to parentItem parentItem.childItems.append(newChildItem) newChildItem.parentItem = parentItem // }
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Does CKSyncEngine have to be re-initialized after an account change event?
According to this comment in the sample project on GitHub and this answer by Apple Staff, CKSyncEngine should be re-initialized after signing out or switching accounts so that "CKSyncEngine schedules a new fetch on init." But according to my tests, CKSyncEngine will schedule a fetch after having a signed out and signed in again, without me ever having to reset the serialized sync state. The documentation doesn't mentioned anywhere that CKSyncEngine should be re-initialized after an account change. In fact, it states that CKSyncEngine will reset its state internally on account changes. So if that's the case, then I'm very confused as to why the "official" recommendation is to re-initialize CKSyncEngine after receiving .signOut or .accountSwitch. Can someone please clarify the correct approach here?
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SwiftData document-based app crashes on undo/redo with autosaveEnabled
Overview I'm developing a document-based app for macOS using SwiftData. When I undo/redo changes using Command-Z/ Command-Shift-Z, the app randomly crashes with the following error: SwiftData/BackingData.swift:425: Fatal error: Failed to retrieve the identifier for \ChildItem.parentItem from KnownKeysDictionary:KnownKeysMap: ["parentItem": 2, "isModified": 1, "index": 0] values: [Optional(0), Optional(false), Optional(DocumentTest.ParentItem)] SwiftData._KKMDBackingData<DocumentTest.ChildItem> And sometimes, instead of the app crashing, my created @Model objects simply disappear. They do not reappear in the @Query on undo/redo. Both of these issues go away when I set modelContext.autosaveEnabled = false The issues are occurring with Xcode 26.4 (17E192) and macOS Tahoe 26.4 (25E246). I have modified the macOS Document App project template to showcase the issue. The project, along with a screen recording of the crash, can be downloaded from here: https://drive.google.com/drive/folders/1aDO34QleTm_rB9BuvVGjzzAP6jDXOc-o?usp=share_link Has anyone else experienced this? I'd like to know if this is a bug in the autosave feature of SwiftData and if I should file a bug report via Feedback Assistant. Steps to Reproduce To recreate the issue, follow these steps: Download and extract the "Xcode Project.zip" file linked above. Open the extracted "DocumentTest" project in Xcode. Build and run the "DocumentTest" app. In the document selection window, click "New Document" at the bottom-left. In the app, click the "+" button at the top-right to add a ParentItem with ChildItems. Click on the added ParentItem's button to modify one of its ChildItems. Repeat steps 5–6 until you have 5 ParentItems with a modified ChildItem. Press Command-Z 10 times to undo all the changes. Press Command-Shift-Z 10 times to redo all the changes. Repeat steps 8–9 until either the app crashes or some of the 5 ParentItems go missing in the list (you may have to repeat them 10–20 times before the issue occurs). If you change line 43 of ContentView.swift to modelContext.autosaveEnabled = false and repeat the same steps above, the app will not crash and no ParentItems will go missing. Code ParentItem Model @Model final class ParentItem { var timestamp: Date @Relationship( deleteRule: .cascade, inverse: \ChildItem.parentItem ) var childItems: [ChildItem] = [] init(timestamp: Date) { self.timestamp = timestamp } } ChildItem Model @Model final class ChildItem { var index: Int var isModified = false var parentItem: ParentItem? init(index: Int) { self.index = index } } Creating, Inserting, and Linking ParentItem and ChildItem // Create and insert ParentItem let newParentItem = ParentItem( timestamp: Date() ) modelContext.insert(newParentItem) // Create and insert ChildItems var newChildItems: [ChildItem] = [] for index in 0..<Int.random(in: 2...8) { let newChildItem = ChildItem(index: index) newChildItems.append(newChildItem) modelContext.insert(newChildItem) } /* Establish relationship between ParentItem and ChildItems */ newParentItem.childItems = newChildItems Modifying ChildItem let firstChildItem = parentItem.childItems .sorted(by: { $0.index < $1.index }).first if let firstChildItem, !firstChildItem.isModified { firstChildItem.isModified = true }
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Production Mac app becomes progressively unusable in Issues workspace; Mac_Dev remains fast
The production macOS build is showing severe performance problems, while Mac_Dev performs normally. Observed behavior in production Mac build: Issue board scrolling becomes inconsistent or nearly unusable Changing an issue status in detail view is very slow Scrolling the status menu/options can be slow Typing in issue description/notes fields becomes sluggish Dragging issues between milestones/statuses on the board can lag badly Observed behavior in Mac_Dev: Board scrolling is smooth Status changes are immediate Typing in description fields is responsive Drag/drop between milestones works well Important comparison: Mac_Dev appears to run against an isolated local SwiftData store Production Mac app uses the normal CloudKit-backed store Because the same UI is fast in Mac_Dev, this does not look like a pure rendering problem Most likely cause is production store / CloudKit sync churn amplifying existing SwiftUI invalidation and save behavior Current hypothesis: The production app is saving or observing live Issue mutations too aggressively Detail view edits and some quick actions may be causing repeated saves / broad view invalidation Cloud-backed persistence likely makes the problem much worse than the isolated dev store The UI architecture may still need cleanup, but the production data lane is likely a major factor Any help in understanding how best to address this would be helpful.
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TestFlight build crashes from fetch descriptor
I have a FetchDescriptor that uses starts(with:) which works fine in debug builds but crashes in TestFlight and archive. For background information I'm using iCloud and model inheritance where the property being used in fetch descriptor is defined on the superclass, the fetch descriptor is for the subclass. Implementation: static func fetchDescriptor(nameStartingWith prefix: String) -> FetchDescriptor<ColorAsset> { let predicate = #Predicate<ColorAsset> { asset in asset.name.starts(with: prefix) } return FetchDescriptor<ColorAsset>(predicate: predicate) } @Model public class Asset: Identifiable { // MARK: - Properties var name: String = "" .... } @available(macOS 26.0, *) @Model public class ColorAsset: Asset { ... }
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Core Data Migration Strategy: store relocation, schema changes and CloudKit adoption in a single release?
I am planning a Core Data migration for a macOS app targeting macOS 12 and later and I would appreciate guidance on structuring the rollout to minimise risk. Context The app currently uses a SQLite store located at: ~/Library/Containers/com.company.AppName/Data/Library/Application Support/AppName I want to: Relocate the persistent store to an app group container: ~/Library/Group Containers/group.com.company.AppName Perform schema migration, including: Renaming attributes Deleting attributes Using a custom NSEntityMigrationPolicy subclass Adopt iCloud sync using NSPersistentCloudKitContainer Potentially leverage staged migration (macOS 14+) Additionally, I intend to port the app to iOS, so the end state needs to support an app group container and CloudKit with the latest schema from the outset. Questions Store relocation vs schema migration Is it advisable to perform store relocation and schema migration in a single step, or should these be separate releases? If combined, are there pitfalls when moving the SQLite file and running a migration in the same launch cycle? Custom migration policy Any best practices for structuring NSEntityMigrationPolicy when also relocating the store? Should migration policies assume the store has already been moved, or handle both concerns? Staged migration (macOS 14+) Is staged migration worth adopting when still supporting macOS 12–13? Would you gate it conditionally, or avoid it entirely for consistency? CloudKit adoption Is introducing NSPersistentCloudKitContainer in the same release as the above migrations too risky? Are there known issues when enabling CloudKit immediately after a migration? Release strategy Would you recommend: A single release handling everything Two phases: (1) store & schema migration, (2) CloudKit Or three phases: store relocation → schema migration → CloudKit Goal I want a smooth, reliable transition without data loss or duplication, particularly for existing users with non-trivial datasets. Any insights, practical experience, or recommended sequencing strategies would be very helpful.
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CoreData + CloudKit -- Many-to-Many Relationship not Syncing
In an iOS App that uses CKShare I have a many-to-many relationship that does not consistently sync between the share's N participants. The relationship is between Group and Player as group.players and player.groups. As an example, given 3 group each with 4 players (aka 4:4:4), some devices show CoreData (it is NOT a UI issue) with 4:2:3 or 3:4:4. (A deletion of CoreData from a device, forcing a full re-sync from CloudKit, seems to populate the group:player relationships consistently; but obviously that is impractical to resolving the issue). How do I avoid these sync-from-CloudKit inconsistencies? Note: AI agents generally suggest adding a CoreData 'join' entity - such as 'GroupPlayer'. Is that THE fix?
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iCloud Sync not working with iPhone, works fine for Mac.
I've been working on an app. It uses iCloud syncing. 48 hours ago everything was working 100%. Make a change on the iPhone it immediately changed on the Mac. Change on the Mac, it immediately changed on the iPhone. I didn't work on it yesterday. I updated to iOS26.4 on the iPhone and 26.4 on the Mac yesterday instead. Today, I pull up the project again. I made NO changes to the code or settings. Make a change on the iPhone it immediately updates on the Mac. Make a change on the Mac, nothing happens on the iPhone. I've waited an hour, and the change never happens. If you leave the iPhone app, then return, it updates as it should. It appears that iCloud's silent notification is to being received by the iPhone. Anyone else having the issue? Is there something new with iOS 26.4 that needs to be adjusted to get this to work? Again, works flawlessly with the Mac, just not with the iPhone.
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CKQuerySubscription on public database never triggers APNS push in Production environment
Hi everyone, I have a SwiftUI app using CKQuerySubscription on the public database for social notifications (friend requests, recommendations, etc.). Push notifications work perfectly in the Development environment but never fire in Production (TestFlight). Setup: iOS 26.4, Xcode 26, Swift 6 Container: public database, CKQuerySubscription with .firesOnRecordCreation 5 subscriptions verified via CKDatabase.allSubscriptions() registerForRemoteNotifications() called unconditionally on every launch Valid APNS device token received in didRegisterForRemoteNotificationsWithDeviceToken Push Notifications + Background Modes (Remote notifications) capabilities enabled What works: All 5 subscriptions create successfully in Production Records are saved and queryable (in-app CloudKit fetches return them immediately) APNS production push works — tested via Xcode Push Notifications Console with the same device token, notification appeared instantly Everything works perfectly in the Development environment (subscriptions fire, push arrives) What doesn't work: When a record is created that matches a subscription predicate, no APNS push is ever delivered in Production Tested with records created from the app (device to device) and from CloudKit Dashboard — neither triggers push Tried: fresh subscription IDs, minimal NotificationInfo (just alertBody), stripped shouldSendContentAvailable, created an APNs key, toggled Push capability in Xcode, re-deployed schema from dev to prod Additional finding: One of my record types (CompletionNotification) was returning BAD_REQUEST when creating a subscription in Production, despite working in Development. Re-deploying the development schema to production (which reported "no changes") fixed the subscription creation. This suggests the production environment had inconsistent subscription state for that record type, possibly from the type being auto-created by a record save before formal schema deployment. I suspect a similar issue may be affecting the subscription-to-APNS pipeline for all my record types — the subscriptions exist and predicates match, but the production environment isn't wiring them to APNS delivery. Subscription creation code (simplified): let subscription = CKQuerySubscription( recordType: "FriendRequest", predicate: NSPredicate(format: "receiverID == %@ AND status == %@", userID, "pending"), subscriptionID: "fr-sub-v3", options: [.firesOnRecordCreation] ) let info = CKSubscription.NotificationInfo() info.titleLocalizationKey = "Friend Request" info.alertLocalizationKey = "FRIEND_REQUEST_BODY" info.alertLocalizationArgs = ["senderUsername"] info.soundName = "default" info.shouldBadge = true info.desiredKeys = ["senderUsername", "senderID"] info.category = "FRIEND_REQUEST" subscription.notificationInfo = info try await database.save(subscription) Has anyone encountered this? Is there a way to "reset" the subscription-to-APNS pipeline for a production container? I'd really appreciate any guidance on how to resolve and get my push notifications back to normal. Many thanks, Dimitar - LaterRex
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Fatal error on rollback after delete
I encountered an error when trying to rollback context after deleting some model with multiple one-to-many relationships when encountered a problem later in a deleting method and before saving the changes. Something like this: do { // Fetch model modelContext.delete(model) // Do some async work that potentially throws try modelContext.save() } catch { modelContext.rollback() } When relationship is empty - the parent has no children - I can safely delete and rollback with no issues. However, when there is even one child when I call even this code: modelContext.delete(someModel) modelContext.rollback() I'm getting a fatal error: SwiftData/ModelSnapshot.swift:46: Fatal error: Unexpected backing data for snapshot creation: SwiftData._FullFutureBackingData<ChildModel> I use ModelContext from within the ModelActor but using mainContext changes nothing. My ModelContainer is quite simple and problem occurs on both in-memory and persistent storage, with or without CloudKit database being enabled. I can isolate the issue in test environment, so the model that's being deleted (or any other) is not being accessed by any other part of the application. However, problem looks the same in the real app. I also changed the target version of iOS from 18.0 to 26.0, but to no avail. My models look kind of like this: @Model final class ParentModel { var name: String @Relationship(deleteRule: .cascade, inverse: \ChildModel.parent) var children: [ChildModel]? init(name: String) { self.name = name } } @Model final class ChildModel { var name: String @Relationship(deleteRule: .nullify) var parent: ParentModel? init(name: String) { self.name = name } } I tried many approaches that didn't help: Fetching all children (via fetch) just to "populate" the context Accessing all children on parent model (via let _ = parentModel.children?.count) Deleting all children reading models from parent: for child in parentModel.children ?? [] { modelContext.delete(child) } Deleting all children like this: let parentPersistentModelID = parentModel.persistentModelID modelContext.delete(model: ChildModel.self, where: #Predicate { $0.parent.persistentModelID == parentPersistentModelID }, includeSubclasses: true) Removing @Relationship(deleteRule: .nullify) from ChildModel relationship definition I found 2 solution for the problem: To manually fetch and delete all children prior to deleting parent: let parentPersistentModelID = parentModel.persistentModelID for child in try modelContext.fetch(FetchDescriptor<ChildModel>(predicate: #Predicate { $0.parent.persistentModelID == parentPersistentModelID })) { modelContext.delete(child) } modelContext.delete(parentModel) Trying to run my code in child context (let childContext = ModelContext(modelContext.container)) All that sounds to me like a problem deep inside Swift Data itself. The first solution I found, fetching potentially hundreds of child models just to delete them in case I might need to rollback changes on some error, sounds like awful waste of resources to me. The second one however seems to work fine has that drawback that I can't fully test my code. Right now I can wrap the context (literally creating class that holds ModelContext and calls its methods) and in tests for throwing methods force them to throw. By creating scratch ModelContext I loose that possibility. What might be the real issue here? Am I missing something?
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SwiftData ModelContext Pollution with Multiple ModelContainers and Schemas
I have two different VersionedSchema accessed via two different and distinct in-memory ModelContainers. However, both schemas have a model named Item. LocalSchema.Item and RemoteSchema.Item have slightly different properties. If I create and save RemoteSchema.Item in one context then I cannot create and save LocalSchema.Item in a different context due to missing origin property. enum LocalSchema: VersionedSchema { static var versionIdentifier: Schema.Version = .init(1, 0, 0) static var models: [any PersistentModel.Type] = [ Item.self ] @Model class Item { @Attribute(.unique) var title: String var created: Date var modified: Date init(title: String, created: Date, modified: Date) { self.title = title self.created = created self.modified = modified } } } enum RemoteSchema: VersionedSchema { static var versionIdentifier: Schema.Version = .init(1, 0, 0) static var models: [any PersistentModel.Type] = [ Item.self ] @Model class Item { var title: String var created: Date var modified: Date var origin: String init(title: String, created: Date, modified: Date, origin: String) { self.title = title self.created = created self.modified = modified self.origin = origin } } } In the above example, saving RemoteSchema.Item will cause LocalSchema.Item to fail. The error message I see is *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<NSManagedObject 0xa120f3750> setValue:forUndefinedKey:]: the entity Item is not key value coding-compliant for the key "origin".' Test Code @Test func createLocalItemWithManualSave() async throws { let context = ModelContext(try localStore()) let item = LocalSchema.Item(title: "local", created: .now, modified: .now) context.insert(item) try context.save() } @Test func createRemoteItemWithManualSave() async throws { let context = ModelContext(try remoteStore()) let item = RemoteSchema.Item(title: "remote", created: .now, modified: .now, origin: "from space") context.insert(item) try context.save() } func localStore() throws -> ModelContainer { let schema = Schema(versionedSchema: LocalSchema.self) let config = ModelConfiguration("local", schema: schema, isStoredInMemoryOnly: true, allowsSave: true, cloudKitDatabase: .none) return try ModelContainer(for: schema, configurations: config) } func remoteStore() throws -> ModelContainer { let schema = Schema(versionedSchema: RemoteSchema.self) let config = ModelConfiguration("remote", schema: schema, isStoredInMemoryOnly: true, allowsSave: true, cloudKitDatabase: .none) return try ModelContainer(for: schema, configurations: config) } I have created FB22310365
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CloudKit, cannot deploy private database initial schema to production
We’re using a private database with a custom zone. Record types and related schema are created programmatically rather than through the dashboard. When running the app in the development environment, I can see that data is saved and can be retrieved successfully. However, in the iCloud console, I don’t see any record types or even the custom zone. Additionally, I’m unable to deploy any schema to production because no changes are detected. Do you have any ideas on what we might be missing? Installing the app from TestFlight when trying to upload a record CloudKit reports this error: <CKError 0x13f40bb10: "Invalid Arguments" (12/2006); server message = "Cannot create new type MyType in production schema" ...>
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CloudKit: Efficient way to get user's rank in leaderboard without fetching all records?
CloudKit: Efficient way to get user's rank in leaderboard without fetching all records? I'm building a leaderboard feature using CloudKit's public database and need advice on the best approach to calculate a user's rank efficiently. Current Setup Record Structure: Record Type: LeaderboardScore Fields: period (String): "daily", "weekly", "monthly", "allTime" score (Int): User's score profile (Reference): Link to user's profile achievedAt (Date): Timestamp Leaderboard Display: Initially fetch first 15 users (sorted by score descending) Paginate to load more as user scrolls Show total player count Show current user's rank (even if not in top 15) The Challenge I can fetch the first 15 users easily with a sorted query, but I need to display the current user's rank regardless of their position. For example: User could be ranked #1 (in top 15) ✅ Easy User could be ranked #247 (not in top 15) ❌ How to get this efficiently? My Current Approach Query records with scores higher than the user's score and count them: // Count how many users scored higher let predicate = NSPredicate( format: "period == %@ AND score > %d", period, userScore ) // Rank = count + 1 Concerns For 1000+ users with better scores, this requires multiple paginated queries Even with desiredKeys: [], I'm concerned about performance and CloudKit request limits Questions Is there a CloudKit API I'm missing that can efficiently count records matching a predicate without fetching all the records and paginating? Is this approach acceptable for a leaderboard with 1K-10K users? Does fetching with desiredKeys: [] help significantly with performance? Are there any optimizations I should consider to make this more efficient? What's the recommended approach for calculating user rank in CloudKit at this scale? Current Scale Expected: 1,000-10,000 active users per leaderboard period Platform: iOS 17+, SwiftUI Any guidance on best practices for leaderboards usecase in CloudKit would be greatly appreciated!
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Orphaning a CKAsset
I'm running into a problem in my attempt to clear CKAssets on the iCloud server. The documentation for CKAsset says: If you no longer require an asset that’s on the server, you don’t delete it. Instead, orphan the asset by setting any fields that contain the asset to nil and then saving the record. CloudKit periodically deletes orphaned assets from the server. I'm deleting image file assets which are properties on an ImageReference type (largeImage and thumbNailImage properties). When I delete an image, I am setting those properties to nil and sending the record for the ImageReference to iCloud using the async CKDatabase.modifyRecords method. This always results in an error: <CKError 0x600000d92a60: "Asset File Not Found" (16/3002); "open error: 2 (No such file or directory)"> And of course the assets still appear in the CloudKit dashboard. What is the proper way of orphaning the assets on the CloudKit server?
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Swift Data Recovery
Hi Writing an app in Swift on Xcode for my iPhone, all software is the latest version. If after making a minor change and re-building all the application data has disappeared, is there a way to see if it is still in the .modelContainer and just not showing up?
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Mar ’26
Cannot create new CloudKit container after deleting all containers - need help
I accidentally deleted all CloudKit containers from the CloudKit Database console, and now I'm unable to create new containers. Both the CloudKit Console website and Xcode are not allowing me to create any new containers. Is there a way to restore the deleted containers? How can I create a new CloudKit container if the console website is not responding? Thank you.
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Mar ’26
SwiftData Models and SortDesc. Only Work in One Swift File
Hey everyone, I found a possible SwiftData Release-only issue with nested sort descriptors on an optional relationship. In a minimal repro, sorting a @Query by a nested optional relationship key path like: SortDescriptor(\InvestigationPhotoAsset.imageAnalysis?.overallAestheticsScore, order: .reverse) works in Debug, but crashes at runtime in Release. The surprising part is that the crash depends on file layout: if the active SwiftData models and the sort logic are kept in the same Swift file, the app works if the same models are split into separate files, the Release build crashes, 'Debug' will also work The repro was reduced to just two SwiftData models: InvestigationPhotoAsset InvestigationImageAnalysis So this looks less like an app-modeling issue and more like a SwiftData/compiler/codegen issue related to nested sort metadata in optimized builds. If useful, I can also give you a slightly more formal version with a title and code snippet block. Please check out the code example here Has anyone faced something similar? Bug is reported as FB22173905
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Missing demo project
Hi forum! I’m currently following a series of videos about SwiftData. In the WWDC23 Build an app with SwiftData video, it mentions that you can follow up with a demo project. However, I’m encountering an issue (at least in my case) where there’s no link on the entire page to download the project. I can download the video and other resources (even using the Developer’s App), but there’s no link for the project. Does anyone else face this issue? Is it possible that the project has been removed? I’m using my developer (single user) account, by the way. Any guidance would be greatly appreciated!
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App Store
I can’t download any games over 18 but I am over 18
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SwiftData document-based app crashes on undo/redo without ModelContext.transaction(block:)
Overview I'm developing a document-based app for macOS using SwiftData. When I undo/redo changes using Command-Z/Command-Shift-Z, the app reliably crashes with the following error: SwiftData/ModelSnapshot.swift:46: Fatal error: Unexpected backing data for snapshot creation: SwiftData._FullFutureBackingData<DocumentTest.ChildItem> And before the app crashes, what always happens is that UndoManager stops removing/restoring instances of ChildItem (but continues to remove/restore instances of ParentItem). The issue goes away when I enclose the relevant code in ModelContext.transaction(block:). However, this shouldn't be necessary, as ModelContext.autosaveEnabled is true by default. The issues are occurring with Xcode 26.4 (17E192) and macOS Tahoe 26.4 (25E246). I have modified the macOS Document App project template to showcase the issue. The sample project, along with a screen recording of the crash, can be downloaded from here: https://drive.google.com/drive/folders/13bCB1qRZ6273BI81zW2zUUBraSvv6p5w?usp=share_link Is this expected behavior or should I file a bug report in Feedback Assistant? Steps to Reproduce To recreate the issue, follow these steps: Download and extract the "Xcode Project.zip" file linked above. Open the extracted "DocumentTest" project in Xcode. Build and run the "DocumentTest" app. In the document selection window, click "New Document" at the bottom-left. In the app, click the "+" button at the top-right to add a ParentItem with ChildItems. Click on the added ParentItem's button to add another ChildItem to it. Repeat steps 5–6 until you have 5 ParentItems with an additional ChildItem. Press Command-Z 10 times to undo all the changes. Press Command-Shift-Z 10 times to redo all the changes. Repeat steps 8–9 until UndoManager stops removing/restoring the additional ChildItem, and continue repeating them until the app eventually crashes (you may have to repeat them 5–10 times before the issue occurs). If you uncomment the ModelContext.transaction(block:) at line 13 of ContentView.swift and repeat the same steps above, no ChildItems will go missing and the app will not crash. Code ParentItem Model @Model final class ParentItem { var timestamp: Date @Relationship( deleteRule: .cascade, inverse: \ChildItem.parentItem ) var childItems: [ChildItem] = [] init(timestamp: Date) { self.timestamp = timestamp } } ChildItem Model @Model final class ChildItem { var index: Int var parentItem: ParentItem? init(index: Int) { self.index = index } } Creating, Inserting, and Linking ParentItem and ChildItem // Create and insert ParentItem let newParentItem = ParentItem( timestamp: Date() ) modelContext.insert(newParentItem) // Create and insert ChildItems var newChildItems: [ChildItem] = [] for index in 0..<Int.random(in: 2...8) { let newChildItem = ChildItem(index: index) newChildItems.append(newChildItem) modelContext.insert(newChildItem) } /* Establish relationship between ParentItem and ChildItems */ for newChildItem in newChildItems { newParentItem.childItems.append( newChildItem ) newChildItem.parentItem = newParentItem } Adding an Additional ChildItem to ParentItem // Uncommenting this block fixes the crash // try! modelContext.transaction { // Create and insert the new ChildItem let newChildItem = ChildItem( index: parentItem.childItems.count ) modelContext.insert(newChildItem) // Establish relationship to parentItem parentItem.childItems.append(newChildItem) newChildItem.parentItem = parentItem // }
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SwiftData document-based app crashes on undo/redo without ModelContext.transaction(block:)
Overview I'm developing a document-based app for macOS using SwiftData. When I undo/redo changes using Command-Z/Command-Shift-Z, the app reliably crashes with the following error: SwiftData/ModelSnapshot.swift:46: Fatal error: Unexpected backing data for snapshot creation: SwiftData._FullFutureBackingData<DocumentTest.ChildItem> And before the app crashes, what always happens is that UndoManager stops removing/restoring instances of ChildItem (but continues to remove/restore instances of ParentItem). The issue goes away when I enclose the relevant code in ModelContext.transaction(block:). However, this shouldn't be necessary, as ModelContext.autosaveEnabled is true by default. The issues are occurring with Xcode 26.4 (17E192) and macOS Tahoe 26.4 (25E246). I have modified the macOS Document App project template to showcase the issue. The sample project, along with a screen recording of the crash, can be downloaded from here: https://drive.google.com/drive/folders/13bCB1qRZ6273BI81zW2zUUBraSvv6p5w?usp=share_link Is this expected behavior or should I file a bug report in Feedback Assistant? Steps to Reproduce To recreate the issue, follow these steps: Download and extract the "Xcode Project.zip" file linked above. Open the extracted "DocumentTest" project in Xcode. Build and run the "DocumentTest" app. In the document selection window, click "New Document" at the bottom-left. In the app, click the "+" button at the top-right to add a ParentItem with ChildItems. Click on the added ParentItem's button to add another ChildItem to it. Repeat steps 5–6 until you have 5 ParentItems with an additional ChildItem. Press Command-Z 10 times to undo all the changes. Press Command-Shift-Z 10 times to redo all the changes. Repeat steps 8–9 until UndoManager stops removing/restoring the additional ChildItem, and continue repeating them until the app eventually crashes (you may have to repeat them 5–10 times before the issue occurs). If you uncomment the ModelContext.transaction(block:) at line 13 of ContentView.swift and repeat the same steps above, no ChildItems will go missing and the app will not crash. Code ParentItem Model @Model final class ParentItem { var timestamp: Date @Relationship( deleteRule: .cascade, inverse: \ChildItem.parentItem ) var childItems: [ChildItem] = [] init(timestamp: Date) { self.timestamp = timestamp } } ChildItem Model @Model final class ChildItem { var index: Int var parentItem: ParentItem? init(index: Int) { self.index = index } } Creating, Inserting, and Linking ParentItem and ChildItem // Create and insert ParentItem let newParentItem = ParentItem( timestamp: Date() ) modelContext.insert(newParentItem) // Create and insert ChildItems var newChildItems: [ChildItem] = [] for index in 0..<Int.random(in: 2...8) { let newChildItem = ChildItem(index: index) newChildItems.append(newChildItem) modelContext.insert(newChildItem) } /* Establish relationship between ParentItem and ChildItems */ for newChildItem in newChildItems { newParentItem.childItems.append( newChildItem ) newChildItem.parentItem = newParentItem } Adding an Additional ChildItem to ParentItem // Uncommenting this block fixes the crash // try! modelContext.transaction { // Create and insert the new ChildItem let newChildItem = ChildItem( index: parentItem.childItems.count ) modelContext.insert(newChildItem) // Establish relationship to parentItem parentItem.childItems.append(newChildItem) newChildItem.parentItem = parentItem // }
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Does CKSyncEngine have to be re-initialized after an account change event?
According to this comment in the sample project on GitHub and this answer by Apple Staff, CKSyncEngine should be re-initialized after signing out or switching accounts so that "CKSyncEngine schedules a new fetch on init." But according to my tests, CKSyncEngine will schedule a fetch after having a signed out and signed in again, without me ever having to reset the serialized sync state. The documentation doesn't mentioned anywhere that CKSyncEngine should be re-initialized after an account change. In fact, it states that CKSyncEngine will reset its state internally on account changes. So if that's the case, then I'm very confused as to why the "official" recommendation is to re-initialize CKSyncEngine after receiving .signOut or .accountSwitch. Can someone please clarify the correct approach here?
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SwiftData document-based app crashes on undo/redo with autosaveEnabled
Overview I'm developing a document-based app for macOS using SwiftData. When I undo/redo changes using Command-Z/ Command-Shift-Z, the app randomly crashes with the following error: SwiftData/BackingData.swift:425: Fatal error: Failed to retrieve the identifier for \ChildItem.parentItem from KnownKeysDictionary:KnownKeysMap: ["parentItem": 2, "isModified": 1, "index": 0] values: [Optional(0), Optional(false), Optional(DocumentTest.ParentItem)] SwiftData._KKMDBackingData<DocumentTest.ChildItem> And sometimes, instead of the app crashing, my created @Model objects simply disappear. They do not reappear in the @Query on undo/redo. Both of these issues go away when I set modelContext.autosaveEnabled = false The issues are occurring with Xcode 26.4 (17E192) and macOS Tahoe 26.4 (25E246). I have modified the macOS Document App project template to showcase the issue. The project, along with a screen recording of the crash, can be downloaded from here: https://drive.google.com/drive/folders/1aDO34QleTm_rB9BuvVGjzzAP6jDXOc-o?usp=share_link Has anyone else experienced this? I'd like to know if this is a bug in the autosave feature of SwiftData and if I should file a bug report via Feedback Assistant. Steps to Reproduce To recreate the issue, follow these steps: Download and extract the "Xcode Project.zip" file linked above. Open the extracted "DocumentTest" project in Xcode. Build and run the "DocumentTest" app. In the document selection window, click "New Document" at the bottom-left. In the app, click the "+" button at the top-right to add a ParentItem with ChildItems. Click on the added ParentItem's button to modify one of its ChildItems. Repeat steps 5–6 until you have 5 ParentItems with a modified ChildItem. Press Command-Z 10 times to undo all the changes. Press Command-Shift-Z 10 times to redo all the changes. Repeat steps 8–9 until either the app crashes or some of the 5 ParentItems go missing in the list (you may have to repeat them 10–20 times before the issue occurs). If you change line 43 of ContentView.swift to modelContext.autosaveEnabled = false and repeat the same steps above, the app will not crash and no ParentItems will go missing. Code ParentItem Model @Model final class ParentItem { var timestamp: Date @Relationship( deleteRule: .cascade, inverse: \ChildItem.parentItem ) var childItems: [ChildItem] = [] init(timestamp: Date) { self.timestamp = timestamp } } ChildItem Model @Model final class ChildItem { var index: Int var isModified = false var parentItem: ParentItem? init(index: Int) { self.index = index } } Creating, Inserting, and Linking ParentItem and ChildItem // Create and insert ParentItem let newParentItem = ParentItem( timestamp: Date() ) modelContext.insert(newParentItem) // Create and insert ChildItems var newChildItems: [ChildItem] = [] for index in 0..<Int.random(in: 2...8) { let newChildItem = ChildItem(index: index) newChildItems.append(newChildItem) modelContext.insert(newChildItem) } /* Establish relationship between ParentItem and ChildItems */ newParentItem.childItems = newChildItems Modifying ChildItem let firstChildItem = parentItem.childItems .sorted(by: { $0.index < $1.index }).first if let firstChildItem, !firstChildItem.isModified { firstChildItem.isModified = true }
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1w
Production Mac app becomes progressively unusable in Issues workspace; Mac_Dev remains fast
The production macOS build is showing severe performance problems, while Mac_Dev performs normally. Observed behavior in production Mac build: Issue board scrolling becomes inconsistent or nearly unusable Changing an issue status in detail view is very slow Scrolling the status menu/options can be slow Typing in issue description/notes fields becomes sluggish Dragging issues between milestones/statuses on the board can lag badly Observed behavior in Mac_Dev: Board scrolling is smooth Status changes are immediate Typing in description fields is responsive Drag/drop between milestones works well Important comparison: Mac_Dev appears to run against an isolated local SwiftData store Production Mac app uses the normal CloudKit-backed store Because the same UI is fast in Mac_Dev, this does not look like a pure rendering problem Most likely cause is production store / CloudKit sync churn amplifying existing SwiftUI invalidation and save behavior Current hypothesis: The production app is saving or observing live Issue mutations too aggressively Detail view edits and some quick actions may be causing repeated saves / broad view invalidation Cloud-backed persistence likely makes the problem much worse than the isolated dev store The UI architecture may still need cleanup, but the production data lane is likely a major factor Any help in understanding how best to address this would be helpful.
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TestFlight build crashes from fetch descriptor
I have a FetchDescriptor that uses starts(with:) which works fine in debug builds but crashes in TestFlight and archive. For background information I'm using iCloud and model inheritance where the property being used in fetch descriptor is defined on the superclass, the fetch descriptor is for the subclass. Implementation: static func fetchDescriptor(nameStartingWith prefix: String) -> FetchDescriptor<ColorAsset> { let predicate = #Predicate<ColorAsset> { asset in asset.name.starts(with: prefix) } return FetchDescriptor<ColorAsset>(predicate: predicate) } @Model public class Asset: Identifiable { // MARK: - Properties var name: String = "" .... } @available(macOS 26.0, *) @Model public class ColorAsset: Asset { ... }
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Core Data Migration Strategy: store relocation, schema changes and CloudKit adoption in a single release?
I am planning a Core Data migration for a macOS app targeting macOS 12 and later and I would appreciate guidance on structuring the rollout to minimise risk. Context The app currently uses a SQLite store located at: ~/Library/Containers/com.company.AppName/Data/Library/Application Support/AppName I want to: Relocate the persistent store to an app group container: ~/Library/Group Containers/group.com.company.AppName Perform schema migration, including: Renaming attributes Deleting attributes Using a custom NSEntityMigrationPolicy subclass Adopt iCloud sync using NSPersistentCloudKitContainer Potentially leverage staged migration (macOS 14+) Additionally, I intend to port the app to iOS, so the end state needs to support an app group container and CloudKit with the latest schema from the outset. Questions Store relocation vs schema migration Is it advisable to perform store relocation and schema migration in a single step, or should these be separate releases? If combined, are there pitfalls when moving the SQLite file and running a migration in the same launch cycle? Custom migration policy Any best practices for structuring NSEntityMigrationPolicy when also relocating the store? Should migration policies assume the store has already been moved, or handle both concerns? Staged migration (macOS 14+) Is staged migration worth adopting when still supporting macOS 12–13? Would you gate it conditionally, or avoid it entirely for consistency? CloudKit adoption Is introducing NSPersistentCloudKitContainer in the same release as the above migrations too risky? Are there known issues when enabling CloudKit immediately after a migration? Release strategy Would you recommend: A single release handling everything Two phases: (1) store & schema migration, (2) CloudKit Or three phases: store relocation → schema migration → CloudKit Goal I want a smooth, reliable transition without data loss or duplication, particularly for existing users with non-trivial datasets. Any insights, practical experience, or recommended sequencing strategies would be very helpful.
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2w
CoreData + CloudKit -- Many-to-Many Relationship not Syncing
In an iOS App that uses CKShare I have a many-to-many relationship that does not consistently sync between the share's N participants. The relationship is between Group and Player as group.players and player.groups. As an example, given 3 group each with 4 players (aka 4:4:4), some devices show CoreData (it is NOT a UI issue) with 4:2:3 or 3:4:4. (A deletion of CoreData from a device, forcing a full re-sync from CloudKit, seems to populate the group:player relationships consistently; but obviously that is impractical to resolving the issue). How do I avoid these sync-from-CloudKit inconsistencies? Note: AI agents generally suggest adding a CoreData 'join' entity - such as 'GroupPlayer'. Is that THE fix?
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iCloud Sync not working with iPhone, works fine for Mac.
I've been working on an app. It uses iCloud syncing. 48 hours ago everything was working 100%. Make a change on the iPhone it immediately changed on the Mac. Change on the Mac, it immediately changed on the iPhone. I didn't work on it yesterday. I updated to iOS26.4 on the iPhone and 26.4 on the Mac yesterday instead. Today, I pull up the project again. I made NO changes to the code or settings. Make a change on the iPhone it immediately updates on the Mac. Make a change on the Mac, nothing happens on the iPhone. I've waited an hour, and the change never happens. If you leave the iPhone app, then return, it updates as it should. It appears that iCloud's silent notification is to being received by the iPhone. Anyone else having the issue? Is there something new with iOS 26.4 that needs to be adjusted to get this to work? Again, works flawlessly with the Mac, just not with the iPhone.
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2w
CKQuerySubscription on public database never triggers APNS push in Production environment
Hi everyone, I have a SwiftUI app using CKQuerySubscription on the public database for social notifications (friend requests, recommendations, etc.). Push notifications work perfectly in the Development environment but never fire in Production (TestFlight). Setup: iOS 26.4, Xcode 26, Swift 6 Container: public database, CKQuerySubscription with .firesOnRecordCreation 5 subscriptions verified via CKDatabase.allSubscriptions() registerForRemoteNotifications() called unconditionally on every launch Valid APNS device token received in didRegisterForRemoteNotificationsWithDeviceToken Push Notifications + Background Modes (Remote notifications) capabilities enabled What works: All 5 subscriptions create successfully in Production Records are saved and queryable (in-app CloudKit fetches return them immediately) APNS production push works — tested via Xcode Push Notifications Console with the same device token, notification appeared instantly Everything works perfectly in the Development environment (subscriptions fire, push arrives) What doesn't work: When a record is created that matches a subscription predicate, no APNS push is ever delivered in Production Tested with records created from the app (device to device) and from CloudKit Dashboard — neither triggers push Tried: fresh subscription IDs, minimal NotificationInfo (just alertBody), stripped shouldSendContentAvailable, created an APNs key, toggled Push capability in Xcode, re-deployed schema from dev to prod Additional finding: One of my record types (CompletionNotification) was returning BAD_REQUEST when creating a subscription in Production, despite working in Development. Re-deploying the development schema to production (which reported "no changes") fixed the subscription creation. This suggests the production environment had inconsistent subscription state for that record type, possibly from the type being auto-created by a record save before formal schema deployment. I suspect a similar issue may be affecting the subscription-to-APNS pipeline for all my record types — the subscriptions exist and predicates match, but the production environment isn't wiring them to APNS delivery. Subscription creation code (simplified): let subscription = CKQuerySubscription( recordType: "FriendRequest", predicate: NSPredicate(format: "receiverID == %@ AND status == %@", userID, "pending"), subscriptionID: "fr-sub-v3", options: [.firesOnRecordCreation] ) let info = CKSubscription.NotificationInfo() info.titleLocalizationKey = "Friend Request" info.alertLocalizationKey = "FRIEND_REQUEST_BODY" info.alertLocalizationArgs = ["senderUsername"] info.soundName = "default" info.shouldBadge = true info.desiredKeys = ["senderUsername", "senderID"] info.category = "FRIEND_REQUEST" subscription.notificationInfo = info try await database.save(subscription) Has anyone encountered this? Is there a way to "reset" the subscription-to-APNS pipeline for a production container? I'd really appreciate any guidance on how to resolve and get my push notifications back to normal. Many thanks, Dimitar - LaterRex
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2w
Fatal error on rollback after delete
I encountered an error when trying to rollback context after deleting some model with multiple one-to-many relationships when encountered a problem later in a deleting method and before saving the changes. Something like this: do { // Fetch model modelContext.delete(model) // Do some async work that potentially throws try modelContext.save() } catch { modelContext.rollback() } When relationship is empty - the parent has no children - I can safely delete and rollback with no issues. However, when there is even one child when I call even this code: modelContext.delete(someModel) modelContext.rollback() I'm getting a fatal error: SwiftData/ModelSnapshot.swift:46: Fatal error: Unexpected backing data for snapshot creation: SwiftData._FullFutureBackingData<ChildModel> I use ModelContext from within the ModelActor but using mainContext changes nothing. My ModelContainer is quite simple and problem occurs on both in-memory and persistent storage, with or without CloudKit database being enabled. I can isolate the issue in test environment, so the model that's being deleted (or any other) is not being accessed by any other part of the application. However, problem looks the same in the real app. I also changed the target version of iOS from 18.0 to 26.0, but to no avail. My models look kind of like this: @Model final class ParentModel { var name: String @Relationship(deleteRule: .cascade, inverse: \ChildModel.parent) var children: [ChildModel]? init(name: String) { self.name = name } } @Model final class ChildModel { var name: String @Relationship(deleteRule: .nullify) var parent: ParentModel? init(name: String) { self.name = name } } I tried many approaches that didn't help: Fetching all children (via fetch) just to "populate" the context Accessing all children on parent model (via let _ = parentModel.children?.count) Deleting all children reading models from parent: for child in parentModel.children ?? [] { modelContext.delete(child) } Deleting all children like this: let parentPersistentModelID = parentModel.persistentModelID modelContext.delete(model: ChildModel.self, where: #Predicate { $0.parent.persistentModelID == parentPersistentModelID }, includeSubclasses: true) Removing @Relationship(deleteRule: .nullify) from ChildModel relationship definition I found 2 solution for the problem: To manually fetch and delete all children prior to deleting parent: let parentPersistentModelID = parentModel.persistentModelID for child in try modelContext.fetch(FetchDescriptor<ChildModel>(predicate: #Predicate { $0.parent.persistentModelID == parentPersistentModelID })) { modelContext.delete(child) } modelContext.delete(parentModel) Trying to run my code in child context (let childContext = ModelContext(modelContext.container)) All that sounds to me like a problem deep inside Swift Data itself. The first solution I found, fetching potentially hundreds of child models just to delete them in case I might need to rollback changes on some error, sounds like awful waste of resources to me. The second one however seems to work fine has that drawback that I can't fully test my code. Right now I can wrap the context (literally creating class that holds ModelContext and calls its methods) and in tests for throwing methods force them to throw. By creating scratch ModelContext I loose that possibility. What might be the real issue here? Am I missing something?
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SwiftData ModelContext Pollution with Multiple ModelContainers and Schemas
I have two different VersionedSchema accessed via two different and distinct in-memory ModelContainers. However, both schemas have a model named Item. LocalSchema.Item and RemoteSchema.Item have slightly different properties. If I create and save RemoteSchema.Item in one context then I cannot create and save LocalSchema.Item in a different context due to missing origin property. enum LocalSchema: VersionedSchema { static var versionIdentifier: Schema.Version = .init(1, 0, 0) static var models: [any PersistentModel.Type] = [ Item.self ] @Model class Item { @Attribute(.unique) var title: String var created: Date var modified: Date init(title: String, created: Date, modified: Date) { self.title = title self.created = created self.modified = modified } } } enum RemoteSchema: VersionedSchema { static var versionIdentifier: Schema.Version = .init(1, 0, 0) static var models: [any PersistentModel.Type] = [ Item.self ] @Model class Item { var title: String var created: Date var modified: Date var origin: String init(title: String, created: Date, modified: Date, origin: String) { self.title = title self.created = created self.modified = modified self.origin = origin } } } In the above example, saving RemoteSchema.Item will cause LocalSchema.Item to fail. The error message I see is *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<NSManagedObject 0xa120f3750> setValue:forUndefinedKey:]: the entity Item is not key value coding-compliant for the key "origin".' Test Code @Test func createLocalItemWithManualSave() async throws { let context = ModelContext(try localStore()) let item = LocalSchema.Item(title: "local", created: .now, modified: .now) context.insert(item) try context.save() } @Test func createRemoteItemWithManualSave() async throws { let context = ModelContext(try remoteStore()) let item = RemoteSchema.Item(title: "remote", created: .now, modified: .now, origin: "from space") context.insert(item) try context.save() } func localStore() throws -> ModelContainer { let schema = Schema(versionedSchema: LocalSchema.self) let config = ModelConfiguration("local", schema: schema, isStoredInMemoryOnly: true, allowsSave: true, cloudKitDatabase: .none) return try ModelContainer(for: schema, configurations: config) } func remoteStore() throws -> ModelContainer { let schema = Schema(versionedSchema: RemoteSchema.self) let config = ModelConfiguration("remote", schema: schema, isStoredInMemoryOnly: true, allowsSave: true, cloudKitDatabase: .none) return try ModelContainer(for: schema, configurations: config) } I have created FB22310365
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CloudKit, cannot deploy private database initial schema to production
We’re using a private database with a custom zone. Record types and related schema are created programmatically rather than through the dashboard. When running the app in the development environment, I can see that data is saved and can be retrieved successfully. However, in the iCloud console, I don’t see any record types or even the custom zone. Additionally, I’m unable to deploy any schema to production because no changes are detected. Do you have any ideas on what we might be missing? Installing the app from TestFlight when trying to upload a record CloudKit reports this error: <CKError 0x13f40bb10: "Invalid Arguments" (12/2006); server message = "Cannot create new type MyType in production schema" ...>
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CloudKit: Efficient way to get user's rank in leaderboard without fetching all records?
CloudKit: Efficient way to get user's rank in leaderboard without fetching all records? I'm building a leaderboard feature using CloudKit's public database and need advice on the best approach to calculate a user's rank efficiently. Current Setup Record Structure: Record Type: LeaderboardScore Fields: period (String): "daily", "weekly", "monthly", "allTime" score (Int): User's score profile (Reference): Link to user's profile achievedAt (Date): Timestamp Leaderboard Display: Initially fetch first 15 users (sorted by score descending) Paginate to load more as user scrolls Show total player count Show current user's rank (even if not in top 15) The Challenge I can fetch the first 15 users easily with a sorted query, but I need to display the current user's rank regardless of their position. For example: User could be ranked #1 (in top 15) ✅ Easy User could be ranked #247 (not in top 15) ❌ How to get this efficiently? My Current Approach Query records with scores higher than the user's score and count them: // Count how many users scored higher let predicate = NSPredicate( format: "period == %@ AND score > %d", period, userScore ) // Rank = count + 1 Concerns For 1000+ users with better scores, this requires multiple paginated queries Even with desiredKeys: [], I'm concerned about performance and CloudKit request limits Questions Is there a CloudKit API I'm missing that can efficiently count records matching a predicate without fetching all the records and paginating? Is this approach acceptable for a leaderboard with 1K-10K users? Does fetching with desiredKeys: [] help significantly with performance? Are there any optimizations I should consider to make this more efficient? What's the recommended approach for calculating user rank in CloudKit at this scale? Current Scale Expected: 1,000-10,000 active users per leaderboard period Platform: iOS 17+, SwiftUI Any guidance on best practices for leaderboards usecase in CloudKit would be greatly appreciated!
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Orphaning a CKAsset
I'm running into a problem in my attempt to clear CKAssets on the iCloud server. The documentation for CKAsset says: If you no longer require an asset that’s on the server, you don’t delete it. Instead, orphan the asset by setting any fields that contain the asset to nil and then saving the record. CloudKit periodically deletes orphaned assets from the server. I'm deleting image file assets which are properties on an ImageReference type (largeImage and thumbNailImage properties). When I delete an image, I am setting those properties to nil and sending the record for the ImageReference to iCloud using the async CKDatabase.modifyRecords method. This always results in an error: <CKError 0x600000d92a60: "Asset File Not Found" (16/3002); "open error: 2 (No such file or directory)"> And of course the assets still appear in the CloudKit dashboard. What is the proper way of orphaning the assets on the CloudKit server?
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Swift Data Recovery
Hi Writing an app in Swift on Xcode for my iPhone, all software is the latest version. If after making a minor change and re-building all the application data has disappeared, is there a way to see if it is still in the .modelContainer and just not showing up?
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Mar ’26
Cannot create new CloudKit container after deleting all containers - need help
I accidentally deleted all CloudKit containers from the CloudKit Database console, and now I'm unable to create new containers. Both the CloudKit Console website and Xcode are not allowing me to create any new containers. Is there a way to restore the deleted containers? How can I create a new CloudKit container if the console website is not responding? Thank you.
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Mar ’26
SwiftData Models and SortDesc. Only Work in One Swift File
Hey everyone, I found a possible SwiftData Release-only issue with nested sort descriptors on an optional relationship. In a minimal repro, sorting a @Query by a nested optional relationship key path like: SortDescriptor(\InvestigationPhotoAsset.imageAnalysis?.overallAestheticsScore, order: .reverse) works in Debug, but crashes at runtime in Release. The surprising part is that the crash depends on file layout: if the active SwiftData models and the sort logic are kept in the same Swift file, the app works if the same models are split into separate files, the Release build crashes, 'Debug' will also work The repro was reduced to just two SwiftData models: InvestigationPhotoAsset InvestigationImageAnalysis So this looks less like an app-modeling issue and more like a SwiftData/compiler/codegen issue related to nested sort metadata in optimized builds. If useful, I can also give you a slightly more formal version with a title and code snippet block. Please check out the code example here Has anyone faced something similar? Bug is reported as FB22173905
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Mar ’26
Missing demo project
Hi forum! I’m currently following a series of videos about SwiftData. In the WWDC23 Build an app with SwiftData video, it mentions that you can follow up with a demo project. However, I’m encountering an issue (at least in my case) where there’s no link on the entire page to download the project. I can download the video and other resources (even using the Developer’s App), but there’s no link for the project. Does anyone else face this issue? Is it possible that the project has been removed? I’m using my developer (single user) account, by the way. Any guidance would be greatly appreciated!
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Mar ’26