I am a novice developer, so please be kind. 😬 I am developing a simple macOS app backed with SwiftData and trying to set up iCloud sync so data syncs between two Macs running the app. I have added the iCloud capability, checked the CloudKit box, and selected an iCloud Container. Per suggestion of Paul Hudson, my model properties have either default values or are marked as optional, and the only relationship in my model is marked as optional. @Model final class Project { // Stable identifier used for restoring selected project across launches. var uuid: UUID? var name: String = "" var active: Bool = true var created: Date = Foundation.Date(timeIntervalSince1970: 0) var modified: Date = Foundation.Date(timeIntervalSince1970: 0) // CloudKit requires to-many relationships to be optional in this schema. @Relationship var timeEntries: [TimeEntry]? init(name: String, active: Bool = true, uuid: UUID? = UUID()) { self.uuid = uuid self.name = name self.active = active self.created = .now self.modified = .now self.timeEntries = [] } @Model final class TimeEntry { // Core timing fields. var start: Date = Foundation.Date(timeIntervalSince1970: 0) var end: Date = Foundation.Date(timeIntervalSince1970: 0) var codeRawValue: String? var activitiesRawValue: String = "" // Inverse relationship back to the owning project. @Relationship(inverse: \Project.timeEntries) var project: Project? init( start: Date = .now, end: Date = .now.addingTimeInterval(60 * 60), code: BillingCode? = nil, activities: [ActivityType] = [] ) { self.start = start self.end = end self.codeRawValue = code?.rawValue self.activitiesRawValue = Self.serializeActivities(activities) } I have set up the following in the AppDelegate for registering for remote notifications as well as some logging to console that the remote notification token was received and to be notified when when I am receiving remote notifications. private final class TimeTrackerAppDelegate: NSObject, NSApplicationDelegate { func applicationDidFinishLaunching(_ notification: Notification) { print("📡 [Push] Registering for remote notifications") NSApplication.shared.registerForRemoteNotifications() } func application(_ application: NSApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) { let tokenPreview = deviceToken.map { String(format: "%02x", $0) }.joined().prefix(16) print("✅ [Push] Registered for remote notifications (token prefix: \(tokenPreview)...)") } func application(_ application: NSApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) { let nsError = error as NSError print("❌ [Push] Failed to register for remote notifications: \(nsError.domain) (\(nsError.code)) \(nsError.localizedDescription)") } func application(_ application: NSApplication, didReceiveRemoteNotification userInfo: [String: Any]) { print("📬 [Push] Received remote notification: \(userInfo)") } } In testing, I run the same commit from Xcode on two different Macs logged into the same iCloud account. My problem is that sync is not reliably working. Starting up the app on both Macs shows that the app successfully registered for remote notifications. Sometimes, making an edit on Mac 1 is immediately reflected in Mac 2 UI along with didReceiveRemoteNotification message (all occurring while the Mac 2 app remains in foreground). Sometimes, the Mac 2 app needs to be backgrounded and re-foregrounded before the UI shows the updated data. Sometimes, an edit on Mac 2 will show on Mac 1 only after re-foregrounded but not show any didReceiveRemoteNotification on the Mac 1 console. Sometimes, an edit on Mac 2 will not show at all on Mac 1 even after re-foregrounding the app. Sometimes, no edits sync between either Mac. I had read about how a few years back, there was a bug in macOS where testing iCloud sync between Macs did not work while running from Xcode but would work in TestFlight. For me, running my app in TestFlight on both Macs has never been able to sync any edits between the Macs. Any idea where I might be going wrong. It seems this should not be this hard and should not be failing so inconsistently. Wondering what I might be doing wrong here.

Hi everyone, I'm looking for the correct architectural guidance for my SwiftData implementation. In my Swift project, I have dedicated async functions for adding, editing, and deleting each of my four models. I created these functions specifically to run certain logic whenever these operations occur. Since these functions are asynchronous, I call them from the UI (e.g., from a button press) by wrapping them in a Task. I've gone through three different approaches and am now stuck. Approach 1: @MainActor Functions Initially, my functions were marked with @MainActor and worked on the main ModelContext. This worked perfectly until I added support for App Intents and Widgets, which caused the app to crash with data race errors. Approach 2: Passing ModelContext as a Parameter To solve the crashes, I decided to have each function receive a ModelContext as a parameter. My SwiftUI views passed the main context (which they get from @Environment(\.modelContext)), while the App Intents and Widgets created and passed in their own private context. However, this approach still caused the app to crash sometimes due to data race errors, especially during actions triggered from the main UI. Approach 3: Creating a New Context in Each Function I moved to a third approach where each function creates its own ModelContext to work on. This has successfully stopped all crashes. However, now the UI actions don't always react or update. For example, when an object is added, deleted, or edited, the change isn't reflected in the UI. I suspect this is because the main context (driving the UI) hasn't been updated yet, or because the async function hasn't finished its work. My Question I'm not sure what to do or what the correct logic should be. How should I structure my data operations to support the main UI, Widgets, and App Intents without causing crashes or UI update failures? Here is the relevant code using my third (and current) approach. I've shortened the helper functions for brevity. // MARK: - SwiftData Operations extension DatabaseManager { /// Creates a new assignment and saves it to the database. public func createAssignment( name: String, deadline: Date, notes: AttributedString, forCourseID courseID: UUID, /*...other params...*/ ) async throws -> AssignmentModel { do { let context = ModelContext(container) guard let course = findCourse(byID: courseID, in: context) else { throw DatabaseManagerError.itemNotFound } let newAssignment = AssignmentModel( name: name, deadline: deadline, notes: notes, course: course, /*...other properties...*/ ) context.insert(newAssignment) try context.save() // Schedule notifications and add to calendar _ = try? await scheduleReminder(for: newAssignment) newAssignment.calendarEventIDs = await CalendarManager.shared.addEventToCalendar(for: newAssignment) try context.save() await MainActor.run { WidgetCenter.shared.reloadTimelines(ofKind: "AppWidget") } return newAssignment } catch { throw DatabaseManagerError.saveFailed } } /// Finds a specific course by its ID in a given context. public func findCourse(byID id: UUID, in context: ModelContext) -> CourseModel? { let predicate = #Predicate<CourseModel> { $0.id == id } let fetchDescriptor = FetchDescriptor<CourseModel>(predicate: predicate) return try? context.fetch(fetchDescriptor).first } } // MARK: - Helper Functions (Implementations omitted for brevity) /// Schedules a local user notification for an event. func scheduleReminder(for assignment: AssignmentModel) async throws -> String { // ... Full implementation to create and schedule a UNNotificationRequest return UUID().uuidString } /// Creates a new event in the user's selected calendars. extension CalendarManager { func addEventToCalendar(for assignment: AssignmentModel) async -> [String] { // ... Full implementation to create and save an EKEvent return [UUID().uuidString] } } Thank you for your help.

Hi, would it be possible that instead of crashing when calling fetchHistory that function simply throws an error instead? fetchHistory seems to crash when it cannot understand the models if they are not compatible etc… which is understandable, but it makes it really difficult to handle and debug, there's not a lot of details, and honestly I would just rather that it throws an error and let me ignore a history entry that might be useless rather than crashing the entire app. Thank you!

Every time I insert a subclass (MYShapeLayer) into the model context, the app crashes with an error: DesignerPlayground crashed due to fatalError in BackingData.swift at line 908. Never access a full future backing data - PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(backing: SwiftData.PersistentIdentifier.PersistentIdentifierBacking.managedObjectID(0xb2dbc55f3f4c57f2 <x-coredata://B1E3206B-40DE-4185-BC65-4540B4705B40/MYShapeLayer/p1>))) with Optional(A6CA4F89-107F-4A66-BC49-DD7DAC689F77) struct ContentView: View { @Environment(\.modelContext) private var modelContext @Query private var designs: [MYDesign] var layers: [MYLayer] { designs.first?.layers ?? [] } var body: some View { NavigationStack { List { ForEach(layers) { layer in Text(layer.description) } } .onAppear { let design = MYDesign(title: "My Design") modelContext.insert(design) try? modelContext.save() } .toolbar { Menu("Add", systemImage: "plus") { Button(action: addTextLayer) { Text("Add Text Layer") } Button(action: addShapeLayer) { Text("Add Shape Layer") } } } } } private func addTextLayer() { if let design = designs.first { let newLayer = MYLayer(order: layers.count, kind: .text) newLayer.design = design modelContext.insert(newLayer) try? modelContext.save() } } private func addShapeLayer() { if let design = designs.first { let newLayer = MYShapeLayer(shapeName: "Ellipse", order: layers.count) newLayer.design = design modelContext.insert(newLayer) try? modelContext.save() } } } #Preview { ContentView() .modelContainer(for: [MYDesign.self, MYLayer.self, MYShapeLayer.self], inMemory: true) } @Model final class MYDesign { var title: String = "" @Relationship(deleteRule: .cascade, inverse: \MYLayer.design) var layers: [MYLayer] = [] init(title: String = "") { self.title = title } } @available(iOS 26.0, macOS 26.0, *) @Model class MYLayer { var design: MYDesign! var order: Int = 0 var title: String = "" init(order: Int = 0, title: String = "New Layer") { self.order = order self.title = title } } @available(iOS 26.0, macOS 26.0, *) @Model class MYShapeLayer: MYLayer { var shapeName: String = "" init(shapeName: String, order: Int = 0) { self.shapeName = shapeName super.init(order: order) } }

Hi everyone, I’m working on an offline-first iOS app using Core Data. I have a question about safe future updates: in my project, I want to be able to add new optional fields to existing Entities or even completely new Entities in future versions — but nothing else (no renaming, deleting, or type changes). Here’s how my current PersistenceController looks: import CoreData struct PersistenceController { static let shared = PersistenceController() let container: NSPersistentContainer init(inMemory: Bool = false) { container = NSPersistentContainer(name: "MyApp") if inMemory { container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null") } container.loadPersistentStores(completionHandler: { (storeDescription, error) in if let error = error as NSError? { print("Core Data failed to load store: \(error), \(error.userInfo)") } }) container.viewContext.automaticallyMergesChangesFromParent = true } } Do I need to explicitly set these properties to ensure lightweight migration works? shouldMigrateStoreAutomatically = true shouldInferMappingModelAutomatically = true Or, according to the documentation, are they already true by default, so I can safely add optional fields and new Entities in future versions without breaking users’ existing data? Thanks in advance for your guidance!

Experiencing a crash that is only reproducible on TestFlight or AppStore version of the app, note this does not happen when running from Xcode. I've isolated the problem to sort argument being added to @Query that fetches a model that sorts based on inherited property. To reproduce: @Model class SuperModel { var createdAt: Date = .now } @available(macOS 26.0, *) @Model class SubModel: SuperModel { } @Query(sort: \SubModel.createdAt, animation: .default) private var models: [SubModel]

I'm developing a SwiftUI app using SwiftData and encountering a persistent issue: Error Message: Thread 1: Fatal error: Duplicate keys of type 'Bland' were found in a Dictionary. This usually means either that the type violates Hashable's requirements, or that members of such a dictionary were mutated after insertion. Details: Occurrence: The error always occurs on the first launch of the app after installation. Specifically, it happens approximately 1 minute after the app starts. Inconsistent Behavior: Despite no changes to the code or server data, the error occurs inconsistently. Data Fetching Process: I fetch data for entities (Bland, CrossZansu, and Trade) from the server using the following process: Fetch Bland and CrossZansu entities via URLSession. Insert or update these entities into the SwiftData context. The fetched data is managed as follows: func refleshBlandsData() async throws { if let blandsOnServer = try await DataModel.shared.getBlands() { await MainActor.run { blandsOnServer.forEach { blandOnServer in if let blandOnLocal = blandList.first(where: { $0.code == blandOnServer.code }) { blandOnLocal.update(serverBland: blandOnServer) } else { modelContext.insert(blandOnServer.bland) } } } } } This is a simplified version of my StockListView. The blandList is a @Query property and dynamically retrieves data from SwiftData: struct StockListView: View { @Environment(\.modelContext) private var modelContext @Query(sort: \Bland.sname) var blandList: [Bland] @Query var users: [User] @State private var isNotLoaded = true @State private var isLoading = false @State private var loadingErrorState = "" var body: some View { NavigationStack { List { ForEach(blandList, id: \.self) { bland in NavigationLink(value: bland) { Text(bland.sname) } } } .navigationTitle("Stock List") .onAppear { doIfFirst() } } } // This function handles data loading when the app launches for the first time func doIfFirst() { if isNotLoaded { loadDataWithAnimationIfNotLoading() isNotLoaded = false } } // This function ensures data is loaded with an animation and avoids multiple triggers func loadDataWithAnimationIfNotLoading() { if !isLoading { isLoading = true Task { do { try await loadData() } catch { // Capture and store any errors during data loading loadingErrorState = "Data load failed: \(error.localizedDescription)" } isLoading = false } } } // Fetch data from the server and insert it into the SwiftData model context func loadData() async throws { if let blandsOnServer = try await DataModel.shared.getBlands() { for bland in blandsOnServer { // Avoid inserting duplicate keys by checking for existing items in blandList if !blandList.contains(where: { $0.code == bland.code }) { modelContext.insert(bland.bland) } } } } } Entity Definitions: Here are the main entities involved: Bland: @Model class Bland: Identifiable { @Attribute(.unique) var code: String var sname: String @Relationship(deleteRule: .cascade, inverse: \CrossZansu.bland) var zansuList: [CrossZansu] @Relationship(deleteRule: .cascade, inverse: \Trade.bland) var trades: [Trade] } CrossZansu: @Model class CrossZansu: Equatable { @Attribute(.unique) var id: String var bland: Bland? } Trade: @Model class Trade { @Relationship(deleteRule: .nullify) var user: User? var bland: Bland } User: class User { var id: UUID @Relationship(deleteRule: .cascade, inverse: \Trade.user) var trades: [Trade] } Observations: Error Context: The error occurs after the data is fetched and inserted into SwiftData. This suggests an issue with Hashable requirements or duplicate keys being inserted unintentionally. Concurrency Concerns: The fetch and update operations are performed in asynchronous tasks. Could this cause race conditions? Questions: Could this issue be related to how @Relationship and @Attribute(.unique) are managed in SwiftData? What are potential pitfalls with Equatable implementations (e.g., in CrossZansu) when used in SwiftData entities? Are there any recommended approaches for debugging "Duplicate keys" errors in SwiftData? Additional Info: Error Timing: The error occurs only during the app's first launch and consistently within the first minute.

I have a single multiplatform application that I use NSPersistentCloudKitContainer on. This works great, except I noticed when I open two instances of the same process (not windows) on the same computer, which share the same store, data duplication and "Metadata Inconsistency" errors start appearing. This answer (https://stackoverflow.com/a/67243833) says this is not supported with NSPersistentCloudKitContainer. Is this indeed true? If it isn't allowed, is the only solution to disable multiple instances of the process via a lock file? I was thinking one could somehow coordinate a single "leader" process that syncs to the cloud, with the others using NSPersistentContainer, but this would be complicated when the "leader" process terminates. Currently, it seems iPad split views are new windows, not processes -- but overall I'm still curious :0 Thank you!

Hello Apple Team, We’re building a CloudKit-enabled Core Data app and would like clarification on the behavior and performance characteristics of Binary Data attributes with “Allows External Storage” enabled when used with NSPersistentCloudKitContainer. Initially, we tried storing image files manually on disk and only saving the metadata (file URLs, dimensions, etc.) in Core Data. While this approach reduced the size of the Core Data store, it introduced instability after app updates and broke sync between devices. We would prefer to use the official Apple-recommended method and have Core Data manage image storage and CloudKit syncing natively. Specifically, we’d appreciate guidance on the following: When a Binary Data attribute is marked as “Allows External Storage”, large image files are stored as separate files on device rather than inline in the SQLite store. How effective is this mechanism in keeping the Core Data store size small on device? Are there any recommended size thresholds or known limits for how many externally stored blobs can safely be managed this way? How are these externally stored files handled during CloudKit sync? Does each externally stored Binary Data attribute get mirrored to CloudKit as a CKAsset? Does external storage reduce the sync payload size or network usage, or is the full binary data still uploaded/downloaded as part of the CKAsset? Are there any bandwidth implications for users syncing via their private CloudKit database, versus developer costs in the public CloudKit database? Is there any difference in CloudKit or Core Data behavior when a Binary Data attribute is managed this way versus manually storing image URLs and handling the file separately on disk? Our goal is to store user-generated images efficiently and safely sync them via CloudKit, without incurring excessive local database bloat or CloudKit network overhead. Any detailed guidance or internal performance considerations would be greatly appreciated. Thank you, Paul Barry Founder & Lead Developer — Boat Buddy / Vessel Buddy iOS App Archipelago Environmental Solutions Inc.

Starting 20th March 2025, I see an increase in bandwidth and latency for one of my CloudKit projects. I'm using NSPersistentCloudKitContainer to synchronise my data. I haven't changed any CloudKit scheme during that time but shipped an update. Since then, I reverted some changes from that update, which could have led to changes in the sync behaviour. Is anyone else seeing any issues? I would love to file a DTS and use one of my credits for that, but unfortunately, I can't because I cannot reproduce it with a demo project because I cannot travel back in time and check if it also has an increase in metrics during that time. Maybe an Apple engineer can green-light me filing a DTS request, please.

I'm getting the following error message when executing the rollback method in a modelContext, what could be causing this ? SwiftData/ModelSnapshot.swift:46: Fatal error: A ModelSnapshot must be initialized with a known-keys dictionary

There's some logic in my app that first checks to see if a specific CloudKit record zone exists. If it doesn't, it creates the zone, and then my application continues on with its work. The way I've implemented this right now is by catching the zoneNotFound error when I call CKDatabase#recordZone(for:) (docs) and creating the zone when that happens: do { try await db.recordZone(for: zoneID) } catch let ckError as CKError where [.zoneNotFound, .userDeletedZone].contains(ckError.code) { // createZone is a helper function try await createZone(zoneID: zoneID, context: context) } This works great, but every time I do this, an error is logged in CloudKit Console, which creates a lot of noise and makes it harder to see real errors. Is there a way to do this without explicitly triggering a CloudKit error? I just found CKDatabase#recordZones(for:) (docs), which seems like it returns an empty array instead of throwing an error if the zone doesn't exist. Will calling that and looking for a non-empty array work just as well, but without logging lots of errors in the console?

Hi, I was testing the new iOS 18 behavior where NSPersistentCloudKitContainer wipes the local Core Data store if the user logs out of iCloud, for privacy purposes. I ran the tests both with a Core Data + CloudKit app, and a simple one using SwiftData with CloudKit enabled. Results were identical in either case. In my testing, most of the time, the feature worked as expected. When I disabled iCloud for my app, the data was wiped (consistent with say the Notes app, except if you disable iCloud it warns you that it'll remove those notes). When I re-enabled iCloud, the data appeared. (all done through the Settings app) However, in scenarios when NSPersistentCloudKitContainer cannot immediately sync -- say due to rate throttling -- and one disables iCloud in Settings, this wipes the local data store and ultimately results in data loss. This occurs even if the changes to the managed objects are saved (to the local store) -- it's simply they aren't synced in time. It can be a little hard to reproduce the issue, especially since when you exit to the home screen from the app, it generally triggers a sync. To avoid this, I swiped up to the screen where you can choose which apps to close, and immediately closed mine. Then, you can disable iCloud, and run the app again (with a debugger is helpful). I once saw a message with something along the lines of export failed (for my record that wasn't synced), and unfortunately it was deleted (and never synced). Perhaps before NSPersistentCloudKitContainer wipes the local store it ought to force sync with the cloud first?

I'm testing my app before releasing to testers, and my app (both macOS and iOS) is crashing when I perform one operation, but only in the production build. I have data that loads from a remote source, and can be periodically updated. There is an option to delete all of that data from the iCloud data store, unless the user has modified a record. Each table has a flag to indicate that (userEdited). Here's the function that is crashing: func deleteCommonData<T:PersistentModel & SDBuddyModel>(_ type: T.Type) throws { try modelContext.delete(model: T.self, where: #Predicate<T> { !$0.userEdited }) } Here's one of the calls that results in a crash: try modelManager.deleteCommonData(Link.self) Here's the error from iOS Console: SwiftData/DataUtilities.swift:85: Fatal error: Couldn't find \Link.<computed 0x0000000104b9d208 (Bool)> on Link with fields [SwiftData.Schema.PropertyMetadata(name: "id", keypath: \Link.<computed 0x0000000104b09b44 (String)>, defaultValue: Optional("54EC6602-CA7C-4EC7-AC06-16E7F2E22DE7"), metadata: nil), SwiftData.Schema.PropertyMetadata(name: "name", keypath: \Link.<computed 0x0000000104b09b84 (String)>, defaultValue: Optional(""), metadata: nil), SwiftData.Schema.PropertyMetadata(name: "url", keypath: \Link.<computed 0x0000000104b09bc4 (String)>, defaultValue: Optional(""), metadata: nil), SwiftData.Schema.PropertyMetadata(name: "desc", keypath: \Link.<computed 0x0000000104b09c04 (String)>, defaultValue: Optional(""), metadata: nil), SwiftData.Schema.PropertyMetadata(name: "userEdited", keypath: \Link.<computed 0x0000000104b09664 (Bool)>, defaultValue: Optional(false), metadata: nil), SwiftData.Schema.PropertyMetadata(name: "modified", keypath: \Link.<computed 0x0000000104b09c44 (Date)>, defaultVal<…> Here's a fragment of the crash log: Exception Type: EXC_BREAKPOINT (SIGTRAP) Exception Codes: 0x0000000000000001, 0x000000019373222c Termination Reason: Namespace SIGNAL, Code 5, Trace/BPT trap: 5 Terminating Process: exc handler [80543] Thread 0 Crashed: 0 libswiftCore.dylib 0x19373222c _assertionFailure(_:_:file:line:flags:) + 176 1 SwiftData 0x22a222160 0x22a1ad000 + 479584 2 SwiftData 0x22a2709c0 0x22a1ad000 + 801216 3 SwiftData 0x22a221b08 0x22a1ad000 + 477960 4 SwiftData 0x22a27b0ec 0x22a1ad000 + 844012 5 SwiftData 0x22a27b084 0x22a1ad000 + 843908 6 SwiftData 0x22a28182c 0x22a1ad000 + 870444 7 SwiftData 0x22a2809e8 0x22a1ad000 + 866792 8 SwiftData 0x22a285204 0x22a1ad000 + 885252 9 SwiftData 0x22a281c7c 0x22a1ad000 + 871548 10 SwiftData 0x22a27cf6c 0x22a1ad000 + 851820 11 SwiftData 0x22a27cc48 0x22a1ad000 + 851016 12 SwiftData 0x22a27a6b0 0x22a1ad000 + 841392 13 SwiftData 0x22a285b2c 0x22a1ad000 + 887596 14 SwiftData 0x22a285a10 0x22a1ad000 + 887312 15 SwiftData 0x22a285bcc 0x22a1ad000 + 887756 16 SwiftData 0x22a27cf6c 0x22a1ad000 + 851820 17 SwiftData 0x22a27cc48 0x22a1ad000 + 851016 18 SwiftData 0x22a27a6b0 0x22a1ad000 + 841392 19 SwiftData 0x22a27c0d8 0x22a1ad000 + 848088 20 SwiftData 0x22a27a654 0x22a1ad000 + 841300 21 SwiftData 0x22a1be548 0x22a1ad000 + 70984 22 SwiftData 0x22a1cfd64 0x22a1ad000 + 142692 23 SwiftData 0x22a1b9618 0x22a1ad000 + 50712 24 SwiftData 0x22a1d2e8c 0x22a1ad000 + 155276 25 CoreData 0x187fbb568 thunk for @callee_guaranteed () -> (@out A, @error @owned Error) + 28 26 CoreData 0x187fc2300 partial apply for thunk for @callee_guaranteed () -> (@out A, @error @owned Error) + 24 27 CoreData 0x187fc19c4 closure #1 in closure #1 in NSManagedObjectContext._rethrowsHelper_performAndWait<A>(fn:execute:rescue:) + 192 28 CoreData 0x187fbbda8 thunk for @callee_guaranteed @Sendable () -> () + 28 29 CoreData 0x187fbbdd0 thunk for @escaping @callee_guaranteed @Sendable () -> () + 28 30 CoreData 0x187f663fc developerSubmittedBlockToNSManagedObjectContextPerform + 252 31 libdispatch.dylib 0x180336ac4 _dispatch_client_callout + 16 32 libdispatch.dylib 0x18032c940 _dispatch_lane_barrier_sync_invoke_and_complete + 56 33 CoreData 0x187fd7290 -[NSManagedObjectContext performBlockAndWait:] + 364 34 CoreData 0x187fc1fb8 NSManagedObjectContext.performAndWait<A>(_:) + 544 35 SwiftData 0x22a1b877c 0x22a1ad000 + 46972 36 SwiftData 0x22a1be2a8 0x22a1ad000 + 70312 37 SwiftData 0x22a1c0e34 0x22a1ad000 + 81460 38 SwiftData 0x22a23ea94 0x22a1ad000 + 596628 39 SwiftData 0x22a256828 0x22a1ad000 + 694312 40 Sourdough Buddy 0x104e5dc98 specialized ModelManager.deleteCommonData<A>(_:) + 144 (ModelManager.swift:128) [inlined] 41 Sourdough Buddy 0x104e5dc98 closure #1 in SettingsView.clearStarterData.getter + 876 (SettingsView.swift:243) It works if I do the following instead: try modelContext.delete(model: Link.self, where: #Predicate { !$0.userEdited }) Why would the func call work in development, but crash in production? And why does doing the more verbose way work instead? I think this is a bug. Thanks

When my app starts it loads data (of vehicle models, manufacturers, ...) from JSON files into CoreData.  This content is static. Some CoreData entities have fields that can be set by the user, for example an isFavorite boolean field. How do I tell CloudKit that my CoreData objects are 'static' and must not be duplicated on other devices (that will also load it from JSON files). In other words, how can I make sure that the CloudKit knows that the record created from JSON for vehicle model XYZ on one device is the same record that was created from JSON on any other device? I'm using NSPersistentCloudKitContainer.

I have been using the basic NSPersistentContainer with 100k+ records for a while now with no issues. The database size can fluctuate a bit but on average it takes up about 22mb on device. When I switch the container to NSPersistentCloudKitContainer, I see a massive increase in size to ~150mb initially. As the sync engine uploads records to iCloud it has ballooned to over 600mb on device. On top of that, the user's iCloud usage in settings reports that it takes up 1.7gb in the cloud. I understand new tables are added and history tracking is enabled but the size increase seems a bit drastic. I'm not sure how we got from 22mb to 1.7gb with the exact same data. A few other things that are important to note: I import all the 100k+ records at once when testing the different containers. At the time of the initial import there is only 1 relation (an import group record) that all the records are attached to. I save the background context only once after all the records and the import group have been made and added to the context. After the initial import, some of these records may have a few new relations added to them over time. I suppose this could be causing some of the size increase, but its only about 20,000 records that are updated. None of the records include files/ large binary data. Most of the attributes are encrypted. I'm syncing to the dev iCloud environment. When I do make a change to a single attribute in a record, CloudKit reports that every attribute has been modified (not sure if this is normal or not ) Also, When syncing to a new device, the sync can take hours - days. I'm guessing it's having to sync both the new records and the changes, but it exponentially gets slower as more records are downloaded. The console will show syncing activity, but new records are being added at a slower rate as more records are added. After about 50k records, it grinds to a halt and while the console still shows sync activity, only about 100 records are added every hour. All this to say i'm very confused where these issues are coming from. I'm sure its a combination of how i've setup my code and the vast record count, record history, etc. If anyone has any ideas it would be much appreciated.

I have been working on an app for the past few months, and one issue that I have encountered a few times is an error where quick subsequent deletions cause issues with detached tasks that are triggered from some user actions. Inside a Task.detached, I am building an isolated model context, querying for LineItems, then iterating over those items. The crash happens when accessing a Transaction property through a relationship. var byTransactionId: [UUID: [LineItem]] { return Dictionary(grouping: self) { item in item.transaction?.id ?? UUID() } } In this case, the transaction has been deleted, but the relationship existed when the fetch occurred, so the transaction value is non-nil. The crash occurs when accessing the id. This is the error. SwiftData/BackingData.swift:1035: Fatal error: This model instance was invalidated because its backing data could no longer be found the store. PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(backing: SwiftData.PersistentIdentifier.PersistentIdentifierBacking.managedObjectID(0xb43fea2c4bc3b3f5 &lt;x-coredata://A9EFB8E3-CB47-48B2-A7C4-6EEA25D27E2E/Transaction/p1756&gt;))) I see other posts about this error and am exploring some suggestions, but if anyone has any thoughts, they would be appreciated.

I am working on a SwiftUI project using Core Data. I have an entity called AppleUser in my data model, with the following attributes: id (UUID), name (String), email (String), password (String), and createdAt (Date). All attributes are non-optional. I created the corresponding Core Data class files (AppleUser+CoreDataClass.swift and AppleUser+CoreDataProperties.swift) using Xcode’s automatic generation. I also have a PersistenceController that initializes the NSPersistentContainer with the model name JobLinkModel. When I try to save a new AppleUser object using: let user = AppleUser(context: viewContext) user.id = UUID() user.name = "User1" user.email = "..." user.password = "password1" user.createdAt = Date()【The email is correctly formatted, but it has been replaced with “…” for privacy reasons】 try? viewContext.save() I get the following error in the console:Core Data save failed: Foundation._GenericObjCError.nilError, [:] User snapshot: ["id": ..., "name": "User1", "email": "...", "password": "...", "createdAt": ...] All fields have valid values, and the Core Data model seems correct. I have also tried: • Checking that the model name in NSPersistentContainer(name:) matches the .xcdatamodeld file (JobLinkModel) • Ensuring the AppleUser entity Class, Module, and Codegen are correctly set (Class Definition, Current Product Module) • Deleting duplicate or old AppleUser class files • Cleaning Xcode build folder and deleting the app from the simulator • Using @Environment(.managedObjectContext) for the context Despite all this, I still get _GenericObjCError.nilError when saving a new AppleUser object. I want to understand: 1. Why is Core Data failing to save even though all fields are non-nil and correctly assigned? 2. Could this be caused by some residual old class files, or is there something else in the setup that I am missing? 3. What steps should I take to ensure that Core Data properly recognizes the AppleUser entity and allows saving? Any help or guidance would be greatly appreciated.

I'm using SwiftData with CloutKit with a very simple app. Data syncs between iOS, iPadOS, and visionOS, but not macOS. From what I can tell, macOS is never getting CK messages unless I'm running the app from Xcode. I can listen for the CK messages and show a line in a debug overlay. This works perfectly when I run from Xcode. I can see the notifications and see updates in my app. However, if I just launch the app outside of Xcode I will never see any changes or notifications. It is as if the Mac app never even tries to contact CloudKit. Schema has been deployed in the CloudKit console. The app is based on the multi-platform Xcode template. Again, only the macOS version has this issue. Is there some extra permission or setting I need to set up in order to use CloudKit on macOS? @State private var publisher = NotificationCenter.default.publisher(for: NSPersistentCloudKitContainer.eventChangedNotification).receive(on: DispatchQueue.main) .onReceive(publisher) { notification in // Listen for changes in CK events if let userInfo = notification.userInfo, let event = userInfo[NSPersistentCloudKitContainer.eventNotificationUserInfoKey] as? NSPersistentCloudKitContainer.Event { let message = "CloudKit Sync: \(event.type.rawValue) - \(event.succeeded ? "Success" : "Failed") - \(event.description)" // Store for UI display syncNotifications.append(message) if syncNotifications.count > 10 { syncNotifications.removeFirst() } } } .overlay(alignment: .topTrailing) { if !syncNotifications.isEmpty { VStack(alignment: .leading) { ForEach(syncNotifications, id: \.self) { notification in Text(notification) .padding(8) } } .frame(width: 800, height: 500) .cornerRadius(8) .background(Color.secondary.opacity(0.2)) .padding() .transition(.move(edge: .top)) } }

I have an app that from day 1 has used Swiftdata and successfully sync'd across devices with Cloudkit. I have added models to the data in the past and deployed the schema and it continued to sync across devices. Sometime I think in June.2025 I added a new model and built out the UI to display and manage it. I pushed a version to Test Flight (twice over a matter of 2 versions and a couple of weeks) and created objects in the new model in Test Flight versions of the app which should push the info to Cloudkit to update the schema. When I go to deploy the schema though there are no changes. I confirmed in the app that Cloudkit is selected and it's point to the correct container. And when I look in Cloudkit the new model isn't listed as an indes. I've pushed deploy schema changes anyway (more than once) and now the app isn't sync-ing across devices at all (even the pre-existing models aren't sync-ing across devices). I even submitted the first updated version to the app store and it was approved and released. I created objects in the new model in production which I know doesn't create the indexes in the development environment. But this new model functions literally everywhere except Cloudkit and I don't know what else to do to trigger an update.