Hi there, I got two models here: Two Models, with Many-To-Many Relationship @Model final class PresetParams: Identifiable { @Attribute(.unique) var id: UUID = UUID() var positionX: Float = 0.0 var positionY: Float = 0.0 var positionZ: Float = 0.0 var volume: Float = 1.0 @Relationship(deleteRule: .nullify, inverse: \Preset.presetAudioParams) var preset = [Preset]() init(position: SIMD3<Float>, volume: Float) { self.positionX = position.x self.positionY = position.y self.positionZ = position.z self.volume = volume self.preset = [] } var position: SIMD3<Float> { get { return SIMD3<Float>(x: positionX, y: positionY, z: positionZ) } set { positionX = newValue.x positionY = newValue.y positionZ = newValue.z } } } @Model final class Preset: Identifiable { @Attribute(.unique) var id: UUID = UUID() var presetName: String var presetDesc: String? var presetAudioParams = [PresetParams]() // Many-To-Many Relationship. init(presetName: String, presetDesc: String? = nil) { self.presetName = presetName self.presetDesc = presetDesc self.presetAudioParams = [] } } To be honest, I don't fully understand how the @Relationship thing works properly in a Many-To-Many relationship situation. Some tutorials suggest that it's required on the "One" side of an One-To-Many Relationship, while the "Many" side doesn't need it. And then there is an ObservableObject called "ModelActors" to manage all ModelActors, ModelContainer, etc. ModelActors, ModelContainer... class ModelActors: ObservableObject { static let shared: ModelActors = ModelActors() let sharedModelContainer: ModelContainer private init() { var schema = Schema([ // ... Preset.self, PresetParams.self, // ... ]) do { sharedModelContainer = try ModelContainer(for: schema, migrationPlan: MigrationPlan.self) } catch { fatalError("Could not create ModelContainer: \(error.localizedDescription)") } } } And there is a migrationPlan: MigrationPlan // MARK: V102 // typealias ... // MARK: V101 typealias Preset = AppSchemaV101.Preset typealias PresetParams = AppSchemaV101.PresetParams // MARK: V100 // typealias ... enum MigrationPlan: SchemaMigrationPlan { static var schemas: [VersionedSchema.Type] { [ AppSchemaV100.self, AppSchemaV101.self, AppSchemaV102.self, ] } static var stages: [MigrationStage] { [AppMigrateV100toV101, AppMigrateV101toV102] } static let AppMigrateV100toV101 = MigrationStage.lightweight(fromVersion: AppSchemaV100.self, toVersion: AppSchemaV101.self) static let AppMigrateV101toV102 = MigrationStage.lightweight(fromVersion: AppSchemaV101.self, toVersion: AppSchemaV102.self) } // MARK: Here is the AppSchemaV101 enum AppSchemaV101: VersionedSchema { static var versionIdentifier: Schema.Version = Schema.Version(1, 0, 1) static var models: [any PersistentModel.Type] { return [ // ... Preset.self, PresetParams.self ] } } Fails on iOS 18.3.x: "Failed to fulfill link PendingRelationshipLink" So I expected the SwiftData subsystem to work correctly with version control. A good news is that on iOS 18.1 it does work. But it fails on iOS 18.3.x with a fatal Error: "SwiftData/SchemaCoreData.swift:581: Fatal error: Failed to fulfill link PendingRelationshipLink(relationshipDescription: (<NSRelationshipDescription: 0x30377fe80>), name preset, isOptional 0, isTransient 0, entity PresetParams, renamingIdentifier preset, validation predicates (), warnings (), versionHashModifier (null)userInfo {}, destination entity Preset, inverseRelationship (null), minCount 0, maxCount 0, isOrdered 0, deleteRule 1, destinationEntityName: "Preset", inverseRelationshipName: Optional("presetAudioParams")), couldn't find inverse relationship 'Preset.presetAudioParams' in model" Fails on iOS 17.5: Another Error I tested it on iOS 17.5 and found another issue: Accessing or mutating the "PresetAudioParams" property causes the SwiftData Macro Codes to crash, affecting both Getter and Setter. It fails with an error: "EXC_BREAKPOINT (code=1, subcode=0x1cc1698ec)" Tweaking the @Relationship marker and ModelContainer settings didn't fix the problem.

Hello, I am building a pretty large database (~40MB) to be used in my SwiftData iOS app as read-only. While inserting and updating the data, I noticed a substantial increase in size (+ ~10MB). A little digging pointed to ACHANGE and ATRANSACTION tables that apparently are dealing with Persistent History Tracking. While I do appreciate the benefits of that, I prefer to save space. Could you please point me in the right direction?

CloudKit CKRecordZone Deletion Issue Problem: CloudKit record zones deleted via CKDatabase.modifyRecordZones(deleting:) or CKModifyRecordZonesOperation are successfully removed but then reappear. I suspect they are automatically reinstated by CloudKit sync, despite successful deletion confirmation. Environment: SwiftData with CloudKit integration Custom CloudKit zones created for legacy zone-based sharing Observed Behavior: Create custom zone (e.g., "TestZone1") via CKDatabase.modifyRecordZones(saving:) Copy records to zone for sharing purposes Delete zone using any CloudKit deletion API - returns success, no errors Immediate verification: Zone is gone from database.allRecordZones() After SwiftData/CloudKit sync or app restart: Zone reappears Reproduction: Tested with three different deletion methods - all exhibit same behaviour: modifyRecordZones(deleting:) async API CKModifyRecordZonesOperation (fire-and-forget) CKModifyRecordZonesOperation with result callbacks Zone deletion succeeds, change tokens (used to track updates to shared records) cleaned up But zones are restored presumably by CloudKit background sync Expected: Deleted zones should remain deleted Actual: Zones are reinstated, creating orphaned zones

For a CRM application, I want users to be able to switch between accounts and have their saved contacts stored locally. Whenever a user logs in, the app should fetch data from their specific database location. What’s the best practice to achieve this? Should I create a separate database for each user? Should I store all the data in one database and filter it by user? Or is there a better approach I should consider?

I have developed an podcast app, where subscriped podcast & episodes synched with iCloud. So its working fine with iOS & iPad with latest os version, but iCloud not synching in iPod with version 15. Please help me to fix this. Thanks Devendra K.

According to my experiments SwiftData does not work with model attributes of primitive type UInt64. More precisely, it crashes in the getter of a UInt64 attribute invoked on an object fetched from the data store. With Core Data persistent UInt64 attributes are not a problem. Does anyone know whether SwiftData will ever support UInt64?

Hi All, I work on a cross platform app, iOS/macOS. All devises on iOS could synchronize data from Coredata : I create a client, I see him an all iOS devices. But when I test on macOs (with TestFlight) the Mac app could not get any information from iOs devices. On Mac, cloud drive is working because I could download and upload documents and share it between all devices, so the account is working but with my App on MacOS, there is no synchronisation. idea????

Hi everyone, Im trying to set up CloudKit for my Unreal Engine 5.4 project but seem to be hitting some roadblocks on how to set up the Record Types. From my understanding I need to set up a "file" record type with a "contents" asset field - but even with this it doesn't seem to work :( Any unreal engine devs with some experience on this who could help me out? Thanks!

Hi everyone, I am experiencing an iCloud provisioning problem I cannot resolve, and Developer Support has not been able to help. My App ID: com.exaqservices.ArkyvTiles Symptoms: 1. In Xcode (v16.2), enabling iCloud in Signing & Capabilities repeatedly fails with: The app ID does not include the iCloud container. Click Try Again. Clicking Try Again does nothing. The error persists forever. 2. In Certificates, Identifiers & Profiles: • The iCloud capability is enabled for this App ID. • The CloudKit container is selected. • But the portal no longer shows the “iCloud Documents” checkbox, which used to be required for ubiquitous document support. 3. Xcode cannot regenerate provisioning profiles because it claims the App ID is missing the iCloud container — even though the container is attached. 4. Provisioning profiles on the Apple Developer site all appear expired, and new ones do not generate correctly. 5. The App Store Connect interface also does not show an iCloud Services section under App Information → Capabilities as older guides describe. Expected Behavior: Since iCloud and the CloudKit container are enabled on the App ID, Xcode should successfully enable: • com.apple.developer.icloud-services • com.apple.developer.icloud-container-identifiers • com.apple.developer.ubiquity-container-identifiers (if needed) • com.apple.developer.ubiquity-kvstore-identifier Instead, the entitlements never propagate. What I suspect: This seems like an App ID metadata mismatch or a stale backend entry where: • the CloudKit container is attached but the entitlement isn’t linked, • the “iCloud Documents” flag is missing due to a UI transition, • provisioning profiles cannot be regenerated because the App ID is not updating correctly. What I need help with: Can someone from Apple engineering confirm: • Whether my App ID metadata is corrupted, • If entitlements need to be manually refreshed, • Or if the “iCloud Documents” toggle has moved or is no longer exposed? This is blocking development completely — I cannot build, sign, or deploy the app with iCloud. Thank you! Alan Metzger

I'm implementing SwiftData with inheritance in an app. I have an Entity class with a property name. This class is inherited by two other classes: Store and Person. The Entity model has a one-to-many relationship with a Transaction class. I can list all my Entity models in a List with a @Query annotation without a problem. However, then I try to access the name property of an Entity from a Transaction relationship, the app crashes with the following error: Thread 1: Fatal error: Never access a full future backing data - PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(backing: SwiftData.PersistentIdentifier.PersistentIdentifierBacking.managedObjectID(0x96530ce28d41eb63 <x-coredata://DABFF7BB-C412-474E-AD50-A1F30AC6DBE9/Person/p4>))) with Optional(F07E7E23-F8F0-4CC0-B282-270B5EDDC7F3) From my attempts to fix the issue, I noticed that: The crash seems related to the relationships with classes that has inherit from another class, since it only happens there. When I create new data, I can usually access it without any problem. The crash mostly happens after reloading the app. This error has been mentioned on the forum (for example here), but in a context not related with inheritance. You can find the full code here. For reference, my models looks like this: @Model class Transaction { @Attribute(.unique) var id: String var name: String var date: Date var amount: Double var entity: Entity? var store: Store? { entity as? Store } var person: Person? { entity as? Person } init( id: String = UUID().uuidString, name: String, amount: Double, date: Date = .now, entity: Entity? = nil, ) { self.id = id self.name = name self.amount = amount self.date = date self.entity = entity } } @Model class Entity: Identifiable { @Attribute(.preserveValueOnDeletion) var name: String var lastUsedAt: Date @Relationship(deleteRule: .cascade, inverse: \Transaction.entity) var operations: [Transaction] init( name: String, lastUsedAt: Date = .now, operations: [Transaction] = [], ) { self.name = name self.lastUsedAt = lastUsedAt self.operations = operations } } @available(iOS 26, *) @Model class Store: Entity { @Attribute(.unique) var id: String var locations: [Location] init( id: String = UUID().uuidString, name: String, lastUsedAt: Date = .now, locations: [Location] = [], operations: [Transaction] = [] ) { self.locations = locations self.id = id super.init(name: name, lastUsedAt: lastUsedAt, operations: operations) } } In order to reproduce the error: Run the app in the simulator. Click the + button to create a new transaction. Relaunch the app, then click on any transaction. The app crashes when it tries to read te name property while building the details view.

Apple's iCloud File Management documentation says to "avoid special punctuation or other special characters" in filenames, but doesn't specify which characters. I need a definitive list to implement filename sanitization in my shipping app. Confirmed issues Our iOS app (CyberTuner, App Store, 15 years shipping on App Store) manages .rcta files in the iCloud ubiquity container via NSFileManager APIs. We've confirmed two characters causing sync failures: Ampersand (&): A file named Yamaha CP70 & CP80.rcta caused repeated "couldn't be backed up" dialogs. ~12 users reported this independently. Replacing & resolved it immediately. No other files in the same directory were affected. Percent (%): A file with % in the filename was duplicated by iCloud sync (e.g., filename% 1.rcta, filename% 2.rcta), and the original was lost. Currently reproducing across multiple devices. Both characters have special meaning in URL encoding (% is the escape character, & is the query parameter separator), which suggests the issue may be in URL handling within the sync pipeline. What I'm looking for: A definitive list of characters that cause problems in the iCloud sync pipeline specifically — not APFS restrictions, but CloudDocs/FileProvider/server-side issues. Confirmation whether these characters are problematic: & % # ? + / : * " < > | Is there a system API for validating or sanitizing filenames for iCloud compatibility before writing to the ubiquity container? Our users are piano technicians who naturally name files "Steinway & Sons" — we need to know exactly what to sanitize rather than guessing. Environment: iOS 17–26, Xcode 26.1, APFS, NSFileManager ubiquity container APIs Bundle FEEDBACK ASSISTANT ID FB21900837

After copying and inserting instances I am getting strange duplicate values in arrays before saving. My models: @Model class Car: Identifiable { @Attribute(.unique) var name: String var carData: CarData func copy() -> Car { Car( name: "temporaryNewName", carData: carData ) } } @Model class CarData: Identifiable { var id: UUID = UUID() var featuresA: [Feature] var featuresB: [Feature] func copy() -> CarData { CarData( id: UUID(), featuresA: featuresA, featuresB: featuresB ) } } @Model class Feature: Identifiable { @Attribute(.unique) var id: Int @Attribute(.unique) var name: String @Relationship( deleteRule:.cascade, inverse: \CarData.featuresA ) private(set) var carDatasA: [CarData]? @Relationship( deleteRule:.cascade, inverse: \CarData.featuresB ) private(set) var carDatasB: [CarData]? } The Car instances are created and saved to SwiftData, after that in code: var fetchDescriptor = FetchDescriptor<Car>( predicate: #Predicate<Car> { car in car.name == name } ) let cars = try! modelContext.fetch( fetchDescriptor ) let car = cars.first! print("car featuresA:", car.featuresA.map{$0.name}) //prints ["green"] - expected let newCar = car.copy() newCar.name = "Another car" newcar.carData = car.carData.copy() print("newCar featuresA:", newCar.featuresA.map{$0.name}) //prints ["green"] - expected modelContext.insert(newCar) print("newCar featuresA:", newCar.featuresA.map{$0.name}) //prints ["green", "green"] - UNEXPECTED! /*some code planned here modifying newCar.featuresA, but they are wrong here causing issues, for example finding first expected green value and removing it will still keep the unexpected duplicate (unless iterating over all arrays to delete all unexpected duplicates - not optimal and sloooooow).*/ try! modelContext.save() print("newCar featuresA:", newCar.featuresA.map{$0.name}) //prints ["green"] - self-auto-healed??? Tested on iOS 18.2 simulator and iOS 18.3.1 device. Minimum deployment target: iOS 17.4 The business logic is that new instances need to be created by copying and modifying previously created ones, but I would like to avoid saving before all instances are created, because saving after creating each instance separately takes too much time overall. (In real life scenario there are more than 10K objects with much more properties, updating just ~10 instances with saving takes around 1 minute on iPhone 16 Pro.) Is this a bug, or how can I modify the code (without workarounds like deleting duplicate values) to not get duplicate values between insert() and save()?

Hi, I'm having trouble implementing iCloud Drive in my app. I've already taken the obvious steps, including enabling iCloud Documents in Xcode and selecting a container. This container is correctly specified in my code, and in theory, everything should work. The data generated by my app should be saved to iCloud Drive in addition to local storage. The data does get stored in the Files app, but the automatic syncing to iCloud Drive doesn’t work as expected. I’ve also considered updating my .entitlements file. Since I’m at a loss, I’m reaching out for help maybe I’ve overlooked something important that's causing it not to work. If anyone has an idea, please let me know. Thanks in advance!

Hi all, I recently discovered that I forgot to deploy my CloudKit schema changes from development to production - an oversight that unfortunately went unnoticed for 2.5 months. As a result, any data created during that time was never synced to iCloud and remains only in the local CoreData store. Once I pushed the schema to production, CloudKit resumed syncing new changes as expected. However, this leaves me with a gap: there's now a significant amount of data that would be lost if users delete or reinstall the app. Before I attempt to implement a manual backup or migration strategy, I was wondering: Does NSPersistentCloudKitContainer keep track of local changes that couldn't be synced doe to the missing schema and automatically reattempt syncing them now that the schema is live? If not, what would be the best approach to ensure this "orphaned" data gets saved to CloudKit retroactively. Thanks in advance for any guidance or suggestions.

Using SwiftData and this is the simplest example I could boil down: @Model final class Item { var timestamp: Date var tag: Tag? init(timestamp: Date) { self.timestamp = timestamp } } @Model final class Tag { var timestamp: Date init(timestamp: Date) { self.timestamp = timestamp } } Notice Tag has no reference to Item. So if I create a bunch of items and set their Tag. Later on I add the ability to delete a Tag. Since I haven't added inverse relationship Item now references a tag that no longer exists so so I get these types of errors: SwiftData/BackingData.swift:875: Fatal error: This model instance was invalidated because its backing data could no longer be found the store. PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(url: x-coredata://EEC1D410-F87E-4F1F-B82D-8F2153A0B23C/Tag/p1), implementation: SwiftData.PersistentIdentifierImplementation) I think I understand now that I just need to add the item reference to Tag and SwiftData will nullify all Item references to that tag when a Tag is deleted. But, the damage is already done. How can I iterate through all Items that referenced a deleted tag and set them to nil or to a placeholder Tag? Or how can I catch that error and fix it when it comes up? The crash doesn't occur when loading an Item, only when accessing item.tag?.timestamp, in fact, item.tag?.id is still ok and doesn't crash since it doesn't have to load the backing data. I've tried things like just looping through all items and setting tag to nil, but saving the model context fails because somewhere in there it still tries to validate the old value. Thanks!

Hello everyone, I'm trying to adopt the new Staged Migrations for Core Data and I keep running into an error that I haven't been able to resolve. The error messages are as follows: warning: Multiple NSEntityDescriptions claim the NSManagedObject subclass 'Movie' so +entity is unable to disambiguate. warning: 'Movie' (0x60000350d6b0) from NSManagedObjectModel (0x60000213a8a0) claims 'Movie'. error: +[Movie entity] Failed to find a unique match for an NSEntityDescription to a managed object subclass This happens for all of my entities when they are added/fetched. Movie is an abstract entity subclass, and it has the error error: +[Movie entity] Failed to find which is unique to the subclass entities, but this occurs for all entities. The NSPersistentContainer is loaded only once, and I set the following option after it's loaded: storeDescription.setOption( [stages], forKey: NSPersistentStoreStagedMigrationManagerOptionKey ) The warnings and errors only appear after I fetch or save to context. It happens regardless of whether the database was migrated or not. In my test project, using the generic NSManagedObject with NSEntityDescription.insertNewObject(forEntityName: "MyEntity", into: context) does not cause the issue. However, using the generic NSManagedObject is not a viable option for my app. Setting the module to "Current Project Module" doesn't change anything, except that it now prints "claims 'MyModule.Show'" in the warnings. I have verified that there are no other entities with the same name or renameIdentifier. Has anyone else encountered this issue, or can offer any suggestions on how to resolve it? Thanks in advance for any help!

Hi, I am experiencing main thread freezes from fetching on Main Actor. Attempting to move the function to a background thread, but whenever I reference the TestModel in a nonisolated context or in another model actor, I get this warning: Main actor-isolated conformance of 'TestModel' to 'PersistentModel' cannot be used in actor-isolated context; this is an error in the Swift 6 language mode Is there a way to do this correctly? Recreation, warning on line 13: class TestModel { var property: Bool = true init() {} } struct SendableTestModel: Sendable { let property: Bool } @ModelActor actor BackgroundActor { func fetch() throws -> [SendableTestModel] { try modelContext.fetch(FetchDescriptor<TestModel>()).map { SendableTestModel(property: $0.property) } } }

Environment visionOS 26 Xcode 26 Issue I am experiencing crash when trying to access a [String] from a @Model data, after dismissing an immersiveSpace and opening a WindowGroup. This crash only occurs when trying to access the [String] property of my Model. It works fine with other properties. Thread 1: Fatal error: This backing data was detached from a context without resolving attribute faults: PersistentIdentifier(...) Steps to Reproduce Open WindowGroup Dismiss window, open ImmersiveSpace Dismiss ImmersiveSpace, reopen WindowGroup Any guidance would be appreciated! @main struct MyApp: App { var body: some Scene { WindowGroup(id: "main") { ContentView() } .modelContainer(for: [Item.self]) ImmersiveSpace(id: "immersive") { ImmersiveView() } } } // In SwiftData model @Model class Item { var title: String = "" // Accessing this property works fine var tags: [String] = [] @storageRestrictions(accesses: _$backingData, initializes: _tags) init(initialValue) { _$backingData.setValue(forKey: \. tags, to: initialValue) _tags =_ SwiftDataNoType() } get { _$observationRegistrar.access(self, keyPath: \.tags) **return self getValue(forkey: \.tags)** // Crashes here }

If use a SortDescriptor for a model and sort by some attribute from a relationship, in DEBUG mode it all works fine and sorts. However, in release mode, it is an instant crash. SortDescriptor(.name, order: .reverse) ---- works SortDescriptor(.assignedUser?.name, order: .reverse) ---- works in debug but crash in release. What is the issue here, is it that SwiftData just incompetent to do this?

Hello, I'm trying to work on an iPadOS and macOS app that will rely on the document-based system to create some kind of orientation task to follow. Let say task1.myfile will be a check point regulation from NYC to SF and task2.myfile will be a visit as many key location as you can in SF. The file represent the specific landmark location and rules of the game. And once open, I will be able to read KML/GPS file to evaluate their score based with the current task. But opened GPS files does not have to be stored in the task file itself, it stay alongside. I wanted to use that scenario to experiment with SwiftData (I'm a long time CoreData user, I even wrote my own WebDAV based persistent store back in the day), and so, mix both on file and in memory persistent store, with distribution based on object class. With CoreData it would have been possible, but I do not see how to achieve that with SwiftData and DocumentGroup integration. Any idea how to do that?