One question I often see on DevForums and in my day DTS job is if a Core Data object managed by NSPersistentCloudKitContainer can be shared with other iCloud users. The answer is yes but you need to do it using CloudKit API directly because NSPersistentCloudKitContainer doesn’t support CloudKit shared database (CKContainer.sharedCloudDatabase) today. Assuming you have a Core Data object, let’s say a document, that you’d like to collaborate with your colleagues: You are the document owner and can use NSPersistentCloudKitContainer to fully manages the document and synchronize it across your devices. You can grab a CloudKit record associated with your document from NSPersistentCloudKitContainer using record(for:) or recordID(for:), and share it to your colleagues using UICloudSharingController. See our Sharing CloudKit Data with Other iCloud Users - https://developer.apple.com/documentation/cloudkit/sharing_cloudkit_data_with_other_icloud_users sample for how to share a CloudKit record. After accepting the sharing, your colleague, as a participant, can view or edit the shared document. The document resides in the participant’s CloudKit shared database and you have to manage it with your own code. When your colleague edits and saves the shared document, the changes go to the owner’s private database, and eventually synchronize to NSPersistentCloudKitContainer on the owner side.  As you can see, you need to implement #2 and #3 with your own code because NSPersistentCloudKitContainer can’t manage the data in the participant's shared database. If you have any difficulty after going through the above sample code, you can contact Apple’s DTS for help.

I'm trying to handle the serverRecordChanged return code you get in CKError when you have a conflict and your using the savePolicy of ifServerRecordUnchanged. According to the CKError.Code.serverRecordChanged documentation, I should be receiving all three records that I need to do a 3-way merge. The problem is that the ancestorRecord (CKRecordChangedErrorAncestorRecordKey can also be used to look it up in the userInfo) doesn't actually contain a record. It only contains the record metadata. Is there something I need to be doing to get the full ancestorRecord in the CKError? If not is it possible to query iCloud for the ancestorRecord? Given that iCloud has the change history (as I understand it), then it is theoretically possible. I just don't know how to do it if it is possible. Are 3-way merges even possible? The design of the serverRecordChanged looks like that is the intent, but I can't see how to do it with the data that CloudKit is providing.

I have a SwiftData flashcard app which I am syncing with CloudKit using NSPersistentCloudKitContainer. While syncing itself is working perfectly, I have noticed a dramatic increase in the app size after enabling sync. Specifically, without CloudKit, 15k flashcards results in the default.store file being about 4.5 MB. With CloudKit, default.store is about 67 MB. I have inspected the store and found that most of this increase is due to the ANSCKRECORDMETADATA table. My question is, does implementing CloudKit normally cause this magnitude of increase in storage? If it doesn’t, is there something in my model, schema, implementation, etc. that could be causing it? Below are two other posts describing a similar issue, but neither with a solution. I replied to the first one about a month ago. I then submitted this to Developer Technical Support, but was asked to post my question in the forums, so here it is. Strange behavior with 100k+ records in NSPersistentCloudKitContainer Huge increase in sqlite file size after adopting CloudKit

Hello, My app has had CloudKit enabled for a while, but it's not working. I get the error "Invalid bundle ID for container". Configure CloudKit in your project from TN3164 suggests changing to a new container. I tried changing to a new container, but this leads to data loss. The article recommends: "If your CloudKit container is already used in the production environment and switching to a new container leads to data loss, consider filing a feedback report with the following information to request manually associating your CloudKit container with your app ID." Where can I request this manual association? Is there anything else I can do? Thank you for your time and assistance. I’d appreciate a prompt resolution, as this issue is blocking our update. Looking forward to guidance.

We are trying to solve for the following condition with SwiftData + CloudKit: Lots of data in CloudKit Perform "app-reset" to clear data & App settings and start fresh. Reset data models with try modelContext.delete(model:_) myModel.count() confirms local deletion (0 records); but iCloud Console shows expectedly slow process to delete. Old CloudKit data is returning during the On Boarding process. Questions: • Would making a new iCloud Zone for each reset work around this, as the new zone would be empty? We're having trouble finding details about how to do this with SwiftData. • Would CKSyncEngine have a benefit over the default SwiftData methods? Open to hearing if anyone has experienced a similar challenge and how you worked around it!

I am trying out the new AttributedString binding with SwiftUI’s TextEditor in iOS26. I need to save this to a Core Data database. Core Data has no AttributedString type, so I set the type of the field to “Transformable”, give it a custom class of NSAttributedString, and set the transformer to NSSecureUnarchiveFromData When I try to save, I first convert the Swift AttributedString to NSAttributedString, and then save the context. Unfortunately I get this error when saving the context, and the save isn't persisted: CoreData: error: SQLCore dispatchRequest: exception handling request: <NSSQLSaveChangesRequestContext: 0x600003721140> , <shared NSSecureUnarchiveFromData transformer> threw while encoding a value. with userInfo of (null) Here's the code that tries to save the attributed string: struct AttributedDetailView: View { @ObservedObject var item: Item @State private var notesText = AttributedString() var body: some View { VStack { TextEditor(text: $notesText) .padding() .onChange(of: notesText) { item.attributedString = NSAttributedString(notesText) } } .onAppear { if let nsattributed = item.attributedString { notesText = AttributedString(nsattributed) } else { notesText = "" } } .task { item.attributedString = NSAttributedString(notesText) do { try item.managedObjectContext?.save() } catch { print("core data save error = \(error)") } } } } This is the attribute setup in the Core Data model editor: Is there a workaround for this? I filed FB17943846 if someone can take a look. Thanks.

I'm experiencing the following error with my SwiftData container when running a build: Code=134504 "Cannot use staged migration with an unknown model version." Code Structure - Summary I am using a versionedSchema to store multiple models in SwiftData. I started experiencing this issue when adding two new models in the newest Schema version. Starting from the current public version, V4.4.6, there are two migrations. Migration Summary The first migration is to V4.4.7. This is a lightweight migration removing one attribute from one of the models. This was tested and worked successfully. The second migration is to V5.0.0. This is a custom migration adding two new models, and instantiating instances of the two new models based on data from instances of the existing models. In the initial testing of this version, no issues were observed. Issue and Steps to Reproduce Reproduction of issue: Starting from a fresh build of the publicly released V4.4.6, I run a new build that contains both Schema Versions (V4.4.7 and V5.0.0), and their associated migration stages. This builds successfully, and the container successfully migrates to V5.0.0. Checking the default.store file, all values appear to migrate and instantiate correctly. The second step in reproduction of the issue is to simply stop running the build, and then rebuild, without any code changes. This fails to initialize the model container every time afterwards. Going back to the simulator after successive builds are stopped in Xcode, the app launches and accesses/modifies the model container as normal. Supplementary Issue: I have been putting up with the same, persistent issue in the Xcode Preview Canvas of "Failed to Initialize Model Container" This is a 5 in 6 build issue, where builds will work at random. In the case of previews, I have cleared all data associated with all previews multiple times. The only difference being that the simulator is a 100% failure rate after the initial, successful initialization. I assume this is due to the different build structure of previews. Lastly, of note, the Xcode previews fail at the same line in instantiating the model container as the simulator does. From my research into this issue, people say that the Xcode preview is instantiating from elsewhere. I do have a separate model container set up specifically for canvas previews, but the error does not occur in that container, but rather the app's main container. Possible Contributing Factors & Tested Facts iOS: While I have experienced issues with SwiftData and the complier in iOS 26, I can rule that out as the issue here. This has been tested on simulators running iOS 18.6, 26.0.1, and 26.1, all encountering failures to initialize model container. While in iOS 18, subsequent builds after the successful migration did work, I did eventually encounter the same error and crash. In iOS 26.0.1 and 26.1, these errors come immediately on the second build. Container Initialization for V4.4.6 do { container = try ModelContainer( for: Job.self, JobTask.self, Day.self, Charge.self, Material.self, Person.self, TaskCategory.self, Service.self, migrationPlan: JobifyMigrationPlan.self ) } catch { fatalError("Failed to Initialize Model Container") } Versioned Schema Instance for V4.4.6 (V4.4.7 differs only by versionIdentifier) static var versionIdentifier = Schema.Version(4, 4, 6) static var models: [any PersistentModel.Type] { [Job.self, JobTask.self, Day.self, Charge.self, Material.self, Person.self, TaskCategory.self, Service.self] } Container Initialization for V5.0.0 do { let schema = Schema([Jobify.self, JobTask.self, Day.self, Charge.self, MaterialItem.self, Person.self, TaskCategory.self, Service.self, ServiceJob.self, RecurerRule.self]) container = try ModelContainer( for: schema, migrationPlan: JobifyMigrationPlan.self ) } catch { fatalError("Failed to Initialize Model Container") } Versioned Schema Instance for V5.0.0 static var versionIdentifier = Schema.Version(5, 0, 0) static var models: [any PersistentModel.Type] { [ JobifySchemaV500.Job.self, JobifySchemaV500.JobTask.self, JobifySchemaV500.Day.self, JobifySchemaV500.Charge.self, JobifySchemaV500.Material.self, JobifySchemaV500.Person.self, JobifySchemaV500.TaskCategory.self, JobifySchemaV500.Service.self, JobifySchemaV500.ServiceJob.self, JobifySchemaV500.RecurerRule.self ] } Addressing Differences in Object Names Type-aliasing: All my model types are type-aliased for simplification in view components. All types are aliased as 'JobifySchemeV446.<#Name#>' in V.4.4.6, and 'JobifySchemaV500.<#Name#>' in V5.0.0 Issues with iOS 26: My type-aliases dating back to iOS 17 overlapped with lower level objects in Swift, including 'Job' and 'Material'. These started to be an issue with initializing the model container when running in iOS 26. The type aliases have been renamed since, however the V4.4.6 build with the old names runs and builds perfectly fine in iOS 26 If there is any other code that may be relevant in determining where this error is occurring, I would be happy to add it. My current best theory is simply that I have mistakenly omitted code relevant to the SwiftData Migration.

If I set my build settings "default actor isolation" to MainActor, how do my @ModelActor actors and model classes need to look like ? For now, I am creating instances of my @ModelActor actors and passing my modelContext container and processing all data there. Everything stays in this context. No models are transferred back to MainActor. Now, after changing my project settings, I am getting a huge amount of warnings. Do I need to set all my model classes to non-isolated and the @ModelActor actor as well? Is there any new sample code to cover this topic ... did not find anything for now. Thanks in advance, Marc

Hi! I use Tips with CloudKit and it works very well, however when a user want to remove their data from CloudKit, how to do that? In CoreData with CloudKit area, NSPersistentCloudKitContainer have purgeObjectsAndRecordsInZone to delete both local managed objects and CloudKit records, however there is no information about the TipKit deletion. Does anyone know ideas?

Hi. I'm hoping someone might be able to help us with an issue that's been affecting our standalone watchOS app for some time now. We've encountered consistent crashes on Apple Watch devices when the app enters the background while the device is offline (i.e., no Bluetooth and no Wi-Fi connection). Through extensive testing, we've isolated the problem to the use of NSPersistentCloudKitContainer. When we switch to NSPersistentContainer, the crashes no longer occur. Interestingly, this issue only affects our watchOS app. The same CloudKit-based persistence setup works reliably on our iOS and macOS apps, even when offline. This leads us to believe the issue may be specific to how NSPersistentCloudKitContainer behaves on watchOS when the device is disconnected from the network. We're targeting watchOS 10 and above. We're unsure if this is a misconfiguration on our end or a potential system-level issue, and we would greatly appreciate any insight or guidance.

I have the following struct doing some simple tasks, running a network request and then saving items to Core Data. Per Xcode 26's new default settings (onisolated(nonsending) & defaultIsolation set to MainActor), the struct and its functions run on the main actor, which works fine and I can even safely omit the context.perform call because of it, which is great. struct DataHandler { func importGames(withIDs ids: [Int]) async throws { ... let context = PersistenceController.shared.container.viewContext for game in games { let newGame = GYGame(context: context) newGame.id = UUID() } try context.save() } } Now, I want to run this in a background thread to increase performance and responsiveness. So I followed this session (https://developer.apple.com/videos/play/wwdc2025/270) and believe the solution is to mark the struct as nonisolated and the function itself as @concurrent. The function now works on a background thread, but I receive a crash: _dispatch_assert_queue_fail. This happens whether I wrap the Core Data calls with context.perform or not. Alongside that I get a few new warnings which I have no idea how to work around. So, what am I doing wrong here? What's the correct way to solve this simple use case with Swift 6's new concurrency stuff and the default main actor isolation in Xcode 26? Curiously enough, when setting onisolated(nonsending) to false & defaultIsolation to non isolating, mimicking the previous behavior, the function works without crashing. nonisolated struct DataHandler { @concurrent func importGames(withIDs ids: [Int]) async throws { ... let context = await PersistenceController.shared.container.newBackgroundContext() for game in games { let newGame = GYGame(context: context) newGame.id = UUID() // Main actor-isolated property 'id' can not be mutated from a nonisolated context; this is an error in the Swift 6 language mode } try context.save() } }

I have a SwiftData application that is using CloudKit. If user is on new device. How can I check and fetch data, instead of just waiting for it happen on its own randomly? For example, I have onboarding which I do not want user to go through again if they already have an active installation. Seems like SwiftData is severely limited in pretty much every way, specially any useful CloudKit debugging or control functionality.

I'm using NSPersistentCloudKitContainer with Core Data and I receive errors because my iCloud space is full. The errors printed are the following: <CKError 0x280df8e40: "Quota Exceeded" (25/2035); server message = "Quota exceeded"; op = 61846C533467A5DF; uuid = 6A144513-033F-42C2-9E27-693548EF2150; Retry after 342.0 seconds>. I want to inform the user about this issue, but I can't find a way to access the details of the error. I'm listening to NSPersistentCloudKitContainer.eventChangedNotification, I receive a error of type .partialFailure. But when I want to access the underlying errors, the partialErrorsByItemID property on the error is nil. How can I access this Quota Exceeded error? import Foundation import CloudKit import Combine import CoreData class SyncMonitor { fileprivate var subscriptions = Set<AnyCancellable>() init() { NotificationCenter.default.publisher(for: NSPersistentCloudKitContainer.eventChangedNotification) .sink { notification in if let cloudEvent = notification.userInfo?[NSPersistentCloudKitContainer.eventNotificationUserInfoKey] as? NSPersistentCloudKitContainer.Event { guard let ckerror = cloudEvent.error as? CKError else { return } print("Error: \(ckerror.localizedDescription)") if ckerror.code == .partialFailure { guard let errors = ckerror.partialErrorsByItemID else { return } for (_, error) in errors { if let currentError = error as? CKError { print(currentError.localizedDescription) } } } } } // end of sink .store(in: &subscriptions) } }

The NSPersistentCloudKitContainer synchronization between core data and iCloud was working fine with phone 15.1. Connected a new iPhone iOS 15.5, it gives error: CoreData: debug: CoreData+CloudKit: -[NSCloudKitMirroringDelegate managedObjectContextSaved:](2504): <NSCloudKitMirroringDelegate: 0x28198c000>: Observed context save: <NSPersistentStoreCoordinator: 0x2809c9420> - <NSManagedObjectContext: 0x2819ad520> 2022-12-05 13:32:28.377000-0600 r2nr[340:6373] [error] error: CoreData+CloudKit: -[NSCloudKitMirroringDelegate _importFinishedWithResult:importer:](1245): <PFCloudKitImporter: 0x2837dd740>: Import failed with error: Error Domain=NSCocoaErrorDomain Code=4864 "*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x65, 0x78, 0x61)" UserInfo={NSDebugDescription=*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x65, 0x78, 0x61)} CoreData: error: CoreData+CloudKit: -[NSCloudKitMirroringDelegate _importFinishedWithResult:importer:](1245): <PFCloudKitImporter: 0x2837dd740>: Import failed with error: Error Domain=NSCocoaErrorDomain Code=4864 "*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x65, 0x78, 0x61)" UserInfo={NSDebugDescription=*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x65, 0x78, 0x61)} I go back and try with my old iPhone iOS 15.1, gives same error.

if it set com.apple.CoreData.ConcurrencyDebug 1 as launch arg the app always crashes and i cant proceed into the app. is there a way to only raise a warning for these issues so that i can go into the app and check every place in one session for coredata errors?

I have an app which uses key-value storage and will not sync data past a certain size -- meaning that device "A" will send the data to the cloud but device "B" will never receive the updated data. Device "B" will receive the NSUbiquitousKeyValueStoreDidChangeExternallyNotification that the KVS changed but the data is empty. The data in in the KVS is comprised of 4 keys, each containing a value of NSData generated by NSKeyedArchiver. The NSData is comprised of property-list data types (e.g. numbers, strings, dates, etc.) I've verified that the KVS meets the limits of: A total of 1 MB per app, with a per-key limit of 1 MB A per-key value size limit of 1 MB, and a maximum of 1024 keys A maximum length for key strings is 64 bytes using UTF8 encoding Also, the app has never received an NSUbiquitousKeyValueStoreQuotaViolationChange notification. Of the 4 keys, 3 of them contain no more than 30 KB of data each. However, one of the keys can contain as much as 160 KB of data which will not sync to another device. Strangely, if I constrain the data to 100 KB it will work, however, that is not ideal as it is a fraction of the necessary data. I don't see any errors in the debug log either. Any suggestions on what to try next to get this working?

Hi, I work on a financial app in Brazil and since Beta 1 we're getting several crashes. We already opened a code level support and a few feedback issues, but haven't got any updates on that yet. We were able to resolve some crashes changing some of our implementation but we aren't able to understand what might be happening with this last one. This is the log we got on console: erro 11:55:41.805875-0300 MyApp CoreData: error: Failed to load NSManagedObjectModel with URL 'file:///private/var/containers/Bundle/Application/0B9F47D9-9B83-4CFF-8202-3718097C92AE/MyApp.app/ServerDrivenModel.momd/' We double checked and the momd is inside the bundle. The same app works on any other iOS version and if we build using Xcode directly (without archiving and installing on an iOS26 device) it works as expected. Have anyone else faced a similar error? Any tips or advice on how we can try to solve that?

Hi all, I have setup my app to use SwiftData with CloudKit sync. I have a production environment and development environment. I can reset the development environment for myself and all users in CloudKit console, but I can't reset the production one as it's tried to users' iCloud accounts, so I've added a button in-app for that feature. In the onboarding of my app, I pre-seed the DB with some default objects, which should be persisted between app install. The issue I'm running into is that I'm unable to force-pull these models from iCloud during the onboarding of a clean re-install, which leads to the models later appearing as duplicates once the user has been on the app for a few minutes and it has pulled from their iCloud account. If anyone has any suggestions on how to handle this issue, I would greatly appreciate it.

Hey all, This is my first app with Swift, and first app using CloudKit / iCloud - although I have launched other iOS app successfully. When I created the app, I selected "none" for storage my bundle identifier looks like this: io.mysite.appname I have the iCloud capability added, with CloudKit checked, and the container also checked that looks like this: iCloud.io.mysite.appname Push Notificaitons capability is also added, but there is no configuration. I have tried automatically managed signing, as well as a manually created provisioning profile.. Every time I build the app onto my device - when I check it out in settings, icloud is not listed. When I go through iCloud into icloud drive, the app is also not listed. I have cleaned the build many times, deleted and reinstalled the app on my phone many times. I am definitely logged into iCloud etc. Obviously I have spent plenty of times trying to debug with various LLMs, but we all seem to be at a loss for what I'm missing or doing wrong. Would love any tips or pointers I may be missing, thank you!

Hi, I'm getting a very odd error log in my SwiftData setup for an iOS app. It is implemented to support schema migration. When starting the app, it simply prints the following log twice (seems to be dependent on how many migration steps, I have two steps in my sample code): CoreData: error: Attempting to retrieve an NSManagedObjectModel version checksum while the model is still editable. This may result in an unstable verison checksum. Add model to NSPersistentStoreCoordinator and try again. (Yes there is a mistyped word "verison", this is exactly the log) The code actually fully works. But I have neither CloudKit configured, nor is this app in Production yet. I'm still just developing. Here is the setup and code to reproduce the issue. Development mac version: macOS 15.5 XCode version: 16.4 iOS Simulator version: 18.5 Real iPhone version: 18.5 Project name: SwiftDataDebugApp SwiftDataDebugApp.swift: import SwiftUI import SwiftData @main struct SwiftDataDebugApp: App { var sharedModelContainer: ModelContainer = { let schema = Schema([ Item.self, ]) let modelConfiguration = ModelConfiguration(schema: schema, isStoredInMemoryOnly: false, allowsSave: true) do { return try ModelContainer(for: schema, migrationPlan: ModelMigraitonPlan.self, configurations: [modelConfiguration]) } catch { fatalError("Could not create ModelContainer: \(error)") } }() var body: some Scene { WindowGroup { ContentView() } .modelContainer(sharedModelContainer) } } Item.swift: import Foundation import SwiftData typealias Item = ModelSchemaV2_0_0.Item enum ModelSchemaV1_0_0: VersionedSchema { static var versionIdentifier = Schema.Version(1, 0, 0) static var models: [any PersistentModel.Type] { [Item.self] } @Model final class Item { var timestamp: Date init(timestamp: Date) { self.timestamp = timestamp } } } enum ModelSchemaV2_0_0: VersionedSchema { static var versionIdentifier = Schema.Version(2, 0, 0) static var models: [any PersistentModel.Type] { [Item.self] } @Model final class Item { var timestamp: Date var tags: [Tag] = [] init(timestamp: Date, tags: [Tag]) { self.timestamp = timestamp self.tags = tags } } } enum ModelMigraitonPlan: SchemaMigrationPlan { static var schemas: [any VersionedSchema.Type] { [ModelSchemaV1_0_0.self] } static var stages: [MigrationStage] { [migrationV1_0_0toV2_0_0] } static let migrationV1_0_0toV2_0_0 = MigrationStage.custom( fromVersion: ModelSchemaV1_0_0.self, toVersion: ModelSchemaV2_0_0.self, willMigrate: nil, didMigrate: { context in let items = try context.fetch(FetchDescriptor<ModelSchemaV2_0_0.Item>()) for item in items { item.tags = Array(repeating: "abc", count: Int.random(in: 0...3)).map({ Tag(value: $0) }) } try context.save() } ) } Tag.swift: import Foundation struct Tag: Codable, Hashable, Comparable { var value: String init(value: String) { self.value = value } static func < (lhs: Tag, rhs: Tag) -> Bool { return lhs.value < rhs.value } static func == (lhs: Tag, rhs: Tag) -> Bool { return lhs.value == rhs.value } func hash(into hasher: inout Hasher) { hasher.combine(value) } } ContentView.swift: import SwiftUI import SwiftData struct ContentView: View { @Environment(\.modelContext) private var modelContext @Query private var items: [Item] var body: some View { VStack { List { ForEach(items) { item in VStack(alignment: .leading) { Text(item.timestamp, format: Date.FormatStyle(date: .numeric, time: .standard)) HStack { ForEach(item.tags, id: \.hashValue) { tag in Text("\(tag.value)") } } } } .onDelete(perform: deleteItems) } Button("Add") { addItem() } .padding(.top) } } private func addItem() { withAnimation { let newItem = Item(timestamp: Date(), tags: [Tag(value: "Hi")]) modelContext.insert(newItem) } do { try modelContext.save() } catch { print("Error saving add: \(error.localizedDescription)") } } private func deleteItems(offsets: IndexSet) { withAnimation { for index in offsets { modelContext.delete(items[index]) } } do { try modelContext.save() } catch { print("Error saving delete: \(error.localizedDescription)") } } } #Preview { ContentView() .modelContainer(for: Item.self, inMemory: true) } I hope someone can help, couldn't find anything related to this log at all.