Users have been reporting that the TestFlight version of my app (compiled with Xcode 26 Beta 6 17A5305f) is sometimes crashing on startup. Upon investigating their ips files, it looks like Core Data is locking up internally during its initialization, resulting in iOS killing my app. I have not recently changed my Core Data initialization logic, and it's unclear how I should proceed. Is this a known issue? Any recommended workaround? I have attached the crash stack below. Thanks! crash_log.txt

Hi everyone, I’ve been working on migrating my app (SwimTimes, which helps swimmers track their times) to use Core Data + CKSyncEngine with Swift 6. After many iterations, forum searches, and experimentation, I’ve created a focused sample project that demonstrates the architecture I’m using. The good news: 👉 I believe the crashes I was experiencing are now solved, and the sync behavior is working correctly. 👉 The demo project compiles and runs cleanly with Swift 6. However, before adopting this as the final architecture, I’d like to ask the community (and hopefully Apple engineers) to validate a few critical points, especially regarding Swift 6 concurrency and Core Data contexts. Architecture Overview Persistence layer: Persistence.swift sets up the Core Data stack with a main viewContext and a background context for CKSyncEngine. Repositories: All Core Data access is abstracted into repository classes (UsersRepository, SwimTimesRepository), with async/await methods. SyncEngine: Wraps CKSyncEngine, handles system fields, sync tokens, and bridging between Core Data entities and CloudKit records. ViewModels: Marked @MainActor, exposing @Published arrays for SwiftUI. They never touch Core Data directly, only via repositories. UI: Simple SwiftUI views bound to the ViewModels. Entities: UserEntity → represents swimmers. SwimTimeEntity → times linked to a user (1-to-many). Current Status The project works and syncs across devices. But there are two open concerns I’d like validated: Concurrency & Memory Safety Am I correctly separating viewContext (main/UI) vs. background context (used by CKSyncEngine)? Could there still be hidden risks of race conditions or memory crashes that I’m not catching? Swift 6 Sendable Compliance Currently, I still need @unchecked Sendable in the SyncEngine and repository layers. What is the recommended way to fully remove these workarounds and make the code safe under Swift 6’s stricter concurrency rules? Request Please review this sample project and confirm whether the concurrency model is correct. Suggest how I can remove the @unchecked Sendable annotations safely. Any additional code improvements or best practices would also be very welcome — the intention is to share this as a community resource. I believe once finalized, this could serve as a good reference demo for Core Data + CKSyncEngine + Swift 6, helping others migrate safely. Environment iOS 18.5 Xcode 16.4 macOS 15.6 Swift 6 Sample Project Here is the full sample project on GitHub: 👉 [https://github.com/jarnaez728/coredata-cksyncengine-swift6] Thanks a lot for your time and for any insights! Best regards, Javier Arnáez de Pedro

As of 2025-05-03, when a macOS user enables iCloud Drive synchronization for Desktop & Documents in US region, does iCloud filter xattrs upon upload or later when downloading back to another macOS host? Or is it the case that iCloud has no filtering of third-party xattrs? Where can I find the technical document outlining exactly what iCloud does with xattrs set on macOS host files and folders synchronized with iCloud Drive?

My entity has a startDate (NSTime) attribute where I use the date and time in my detail display of the entity. And in my list, I need to group my entities by day (YYMMDD) based on the start date; and I want to ensure that it can adapt to the region where the user is currently (e.g. if user travels or migrate, the YYMMDD should be adapted based on the current region). Does Core Data SectionedFetchRequest supports strftime() functions from SQLite (https://sqlite.org/lang_datefunc.html) or what is an effective alternative sectioned fetch in my case?

i want to save data like images, text,amd mapviews with swiftui. It is only saved but if you delete the app of buy a new iPhone everything is deleted, how can I make if that the information saved on my app is saved even after I update the app, delete the app, or put the app in another iPhone with SwiftUI? i have watched youtube videos and im still confused,please 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.

I'm trying to set up an application using SwiftData to have a number of models backed by a local datastore that's not synced to CloudKit, and another set of models that is. I was able to achieve this previously with Core Data using multiple NSPersistentStoreDescription instances. The set up code looks something like: do { let fullSchema = Schema([ UnsyncedModel.self, SyncedModel.self, ]) let localSchema = Schema([UnsyncedModel.self]) let localConfig = ModelConfiguration(schema: localSchema, cloudKitDatabase: .none) let remoteSchema = Schema([SyncedModel.self]) let remoteConfig = ModelConfiguration(schema: remoteSchema, cloudKitDatabase: .automatic) container = try ModelContainer(for: fullSchema, configurations: localConfig, remoteConfig) } catch { fatalError("Failed to configure SwiftData container.") } However, it doesn't seem to work as expected. If I remove the synced/remote schema and configuration then everything works fine, but the moment I add in the remote schema and configuration I get various different application crashes. Some examples below: A Core Data error occurred." UserInfo={Reason=Entity named:... not found for relationship named:..., Fatal error: Failed to identify a store that can hold instances of SwiftData._KKMDBackingData<...> Has anyone ever been able to get a similar setup to work using SwiftData?

Hi, I am implementing a premium feature in my app where CloudKit syncing is available only for "Pro" users. The Workflow: Free Users: I initialize the ModelContainer with cloudKitDatabase: .none so their data stays local. Pro Upgrade: When a user purchases a subscription, I restart the container with cloudKitDatabase: .automatic to enable syncing. The Problem: If a user starts as "Free" (creates local data) and later upgrades to "Pro", the app crashes immediately upon launch with the following error: Fatal error: Failed to create ModelContainer: SwiftDataError(_error: SwiftData.SwiftDataError._Error.loadIssueModelContainer, _explanation: nil) It seems that SwiftData fails to load the existing data once the configuration changes to expect a CloudKit-backed store. My Question: Is there a supported way to "toggle" CloudKit on for an existing local dataset without causing this crash? I want the user's existing local data to start syncing once they pay, but currently, it just crashes. My code: import Foundation import SwiftData public enum DataModelEnum: String { case task, calendar public static let container: ModelContainer = { let isSyncEnabled = UserDefaults.isProUser let config = ModelConfiguration( groupContainer: .identifier("group.com.yourcompany.myApp"), cloudKitDatabase: isSyncEnabled ? .automatic : .none ) do { return try ModelContainer(for: TaskModel.self, CalendarModel.self, configurations: config) } catch { fatalError("Failed to create ModelContainer: \(error)") } }() }

While experimenting with CloudKit dashboard, I accidentally turned off a iCloud container. Now in the Certificates, Identifiers & Profiles section of developer portal, this iCloud container identifier is listed under "hidden" not "active" I can edit its name but there is not way to unhide or active it again. What am I missing?

Hi, I'm using SwiftData in my app, and I want to sent data to iCloud with CloudKit, but I found that If the user turns off my App iCloud sync function in the settings App, the local data will also be deleted. A better way is maintaining the local data, just don't connect to iCloud.How should I do that? I need guidance!!! I'm just getting started with CloudKit And I would be appreciated!

Hello, If I want to modify records in my public database, this works fine. However, if I change from public to private in the requesturl, I get the response: "500 - Internal Error". According to the CK WebService Reference, it is possible to access the private database. Could someone explain to me if it is really an internal error and if it could be fixed by Apple, since I would like to access my own private database with the server-to-server key. Thanks in advance.

I'm working on a new app with SwiftData and now adding CloudKit Sync. Everything is working fine in the simulator against the development CloudKit Schema. I successfully deployed the schema to production. However, the TestFlight builds fail against production. This is what I see in the logs, but I haven't been able to find info on how to fix it. Help appreciated. CoreData+CloudKit: -[NSCloudKitMirroringDelegate _requestAbortedNotInitialized:](2205): <private> - Never successfully initialized and cannot execute request '<private>' due to error: Error Domain=CKErrorDomain Code=2 "CKInternalErrorDomain: 1011" UserInfo={ContainerID=<private>, NSDebugDescription=CKInternalErrorDomain: 1011, CKPartialErrors=<private>, RequestUUID=<private>, NSLocalizedDescription=<private>, CKErrorDescription=<private>, NSUnderlyingError=0x1078e9fe0 {Error Domain=CKInternalErrorDomain Code=1011 UserInfo={CKErrorDescription=<private>, NSLocalizedDescription=<private>, CKPartialErrors=<private>}}} CoreData+CloudKit: -[NSCloudKitMirroringDelegate _performSetupRequest:]_block_invoke(1153): <private>: Successfully set up CloudKit integration for store (<private>): <private> CoreData+CloudKit: -[NSCloudKitMirroringDelegate _enqueueRequest:]_block_invoke(1035): Failed to enqueue request: <private> Error Domain=NSCocoaErrorDomain Code=134417 UserInfo={NSLocalizedFailureReason=<private>}

Hi, I’m running into an issue with Core Data migrations using a custom NSMappingModel created entirely in Swift (not using .xcmappingmodel files). Setup: • I’m performing a migration with a manually constructed NSMappingModel • One of the NSEntityMapping instances is configured as follows: • mappingType = .customEntityMappingType (or .transformEntityMappingType) • entityMigrationPolicyClassName is set to a valid subclass of NSEntityMigrationPolicy • The class implements the expected methods like: @objc func createDestinationInstances(…) throws { … } @objc func createCustomDestinationInstance(…) throws -> NSManagedObject { … } The policy class is instantiated (confirmed via logging in init()), but none of the migration methods are ever called. I have also tried adding valid NSPropertyMapping instances with real valueExpression bindings to force activation, but that didn’t make a difference. Constraints: • I cannot use .xcmappingmodel files in this context due to transformable attributes not compatible with the visual editor. • Therefore, I need the entire mapping model to be defined in Swift. Workaround: As a temporary workaround, I’m migrating the data manually using two persistent stores and NSManagedObjectContext, but I’d prefer to rely on NSMigrationManager as designed. Question: Is there a known limitation that prevents Core Data from invoking NSMigrationPolicy methods when using in-memory NSMappingModel instances? Or is there any specific setup required to trigger them when not loading from .xcmappingmodel? Thanks in advance.

I have the following lines of code to access data through CoreData. import Foundation import CoreData import CloudKit class CoreDataManager { static let instance = CoreDataManager() let container: NSPersistentCloudKitContainer let context: NSManagedObjectContext init() { container = NSPersistentCloudKitContainer(name: "ABC") container.loadPersistentStores(completionHandler: { (storeDescription, error) in if let error = error as NSError? { print(error.userInfo) } }) context = container.viewContext context.automaticallyMergesChangesFromParent = true context.mergePolicy = NSMergePolicy(merge: .mergeByPropertyObjectTrumpMergePolicyType) } func save() { do { try container.viewContext.save() print("Saved successfully") } catch { print("Error in saving data: \(error.localizedDescription)") } } } I have confirmed that I can share data between iPhone and iPad. Now, I need to use AppGroup as well. I have changed my code as follows. import Foundation import CoreData import CloudKit class CoreDataManager { static let shared = CoreDataManager() let container: NSPersistentContainer let context: NSManagedObjectContext init() { container = NSPersistentCloudKitContainer(name: "ABC") container.persistentStoreDescriptions = [NSPersistentStoreDescription(url: FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: "some group name")!.appendingPathComponent("CoreDataMama.sqlite"))] container.loadPersistentStores(completionHandler: { (description, error) in if let error = error as NSError? { print("Unresolved error \(error), \(error.userInfo)") } }) context = container.viewContext context.automaticallyMergesChangesFromParent = true context.mergePolicy = NSMergePolicy(merge: .mergeByPropertyObjectTrumpMergePolicyType) } func save() { do { try container.viewContext.save() print("Saved successfully") } catch { print("Error in saving data: \(error.localizedDescription)") } } } Other files being unaltered, my sample apps aren't sharing data. What am I doing wrong? Just FYI, I'm using actual devices. Thank you for your reading this topic.

Hi everyone, Complete newbie here. Building an app and trying to use Cloudkit. I've added the CloudKit capability, triple checked the entitlements file for appropriate keys, made sure the code signing entitlements are pointing to the correct entitlements file. I've removed and cleared all of those settings and even created a new container as well as refreshed the signing. I just can't seem to figure out why I keep getting this error: Significant issue at CKContainer.m:747: In order to use CloudKit, your process must have a com.apple.developer.icloud-services entitlement. The value of this entitlement must be an array that includes the string "CloudKit" or "CloudKit-Anonymous". Any guidance is greatly appreciated.

It takes a few seconds, sometimes a few minutes for records to be downloaded back from CloudKit when the user reinstalls the app, which leads users to thinking their data was lost. I would like to know if there’s any way to provide a visual feedback about the current CloudKit sync status so I can let users know their data is being in fact downloaded back to their devices.

I have a simple app that makes an HTTPS call to gather some JSON which I then parse and add to my SwiftData database. The app then uses a simple @Query in a view to get the data into a list. on iOS 16 this works fine. No problems. But the same code on iOS 26 (targeting iOS 18.5) crashes after about 15 seconds of idle time after the list is populated. The error message is: Could not cast value of type '__NSCFNumber' (0x1f31ee568) to 'NSString' (0x1f31ec718). and occurs when trying to access ANY property of the list. I have a stripped down version of the app that shows the crash available. To replicate the issue: open the project in Xcode 26 target any iOS 26 device or simulator compile and run the project. after the list is displayed, wait about 15 seconds and the app crashes. It is also of note that if you try to run the app again, it will crash immediately, unless you delete the app from the device. Any help on this would be appreciated. Feedback number FB20295815 includes .zip file Below is the basic code (without the data models) The Best Seller List.Swift import SwiftUI import SwiftData @main struct Best_Seller_ListApp: App { var body: some Scene { WindowGroup { ContentView() } .modelContainer (for: NYTOverviewResponse.self) } } ContentView.Swift import os.log import SwiftUI struct ContentView: View { @Environment(\.modelContext) var modelContext @State private var listEncodedName = String() var body: some View { NavigationStack () { ListsView() } .task { await getBestSellerLists() } } func getBestSellerLists() async { guard let url = URL(string: "https://api.nytimes.com/svc/books/v3/lists/overview.json?api-key=\(NYT_API_KEY)") else { Logger.errorLog.error("Invalid URL") return } do { let decoder = JSONDecoder() var decodedResponse = NYTOverviewResponse() //decode the JSON let (data, _) = try await URLSession.shared.data(from: url) decoder.keyDecodingStrategy = .convertFromSnakeCase decodedResponse = try decoder.decode(NYTOverviewResponse.self, from: data) //remove any lists that don't have list_name_encoded. Fixes a bug in the data decodedResponse.results!.lists = decodedResponse.results!.lists!.filter { $0.listNameEncoded != "" } // sort the lists decodedResponse.results!.lists!.sort { (lhs, rhs) -> Bool in lhs.displayName < rhs.displayName } //delete any potential existing data try modelContext.delete(model: NYTOverviewResponse.self) //add the new data modelContext.insert(decodedResponse) } catch { Logger.errorLog.error("\(error.localizedDescription)") } } } ListsView.Swift import os.log import SwiftData import SwiftUI @MainActor struct ListsView: View { //MARK: - Variables and Constants @Query var nytOverviewResponses: [NYTOverviewResponse] enum Updated: String { case weekly = "WEEKLY" case monthly = "MONTHLY" } //MARK: - Main View var body: some View { List { if nytOverviewResponses.isEmpty { ContentUnavailableView("No lists yet", systemImage: "list.bullet", description: Text("NYT Bestseller lists not downloaded yet")) } else { WeeklySection MonthlySection } } .navigationBarTitle("Bestseller Lists", displayMode: .large) .listStyle(.grouped) } var WeeklySection: some View { let rawLists = nytOverviewResponses.last?.results?.lists ?? [] // Build a value-typed array to avoid SwiftData faulting during sort let weekly = rawLists .filter { $0.updateFrequency == Updated.weekly.rawValue } .map { (name: $0.displayName, encoded: $0.listNameEncoded, model: $0) } .sorted { $0.name < $1.name } return Section(header: Text("Weekly lists to be published on \(nytOverviewResponses.last?.results?.publishedDate ?? "-")")) { ForEach(weekly, id: \.encoded) { item in Text(item.name).font(Font.custom("Georgia", size: 17)) } } } var MonthlySection: some View { let rawLists = nytOverviewResponses.last?.results?.lists ?? [] // Build a value-typed array to avoid SwiftData faulting during sort let monthly = rawLists .filter { $0.updateFrequency == Updated.monthly.rawValue } .map { (name: $0.displayName, encoded: $0.listNameEncoded, model: $0) } .sorted { $0.name < $1.name } return Section(header: Text("Monthly lists to be published on \(nytOverviewResponses.last?.results?.publishedDate ?? "-")")) { ForEach(monthly, id: \.encoded) { item in Text(item.name).font(Font.custom("Georgia", size: 17)) } } } }

Hi, thank you for your reply. I have checked and confirmed that all AppleUser entity fields (id, name, email, password, createdAt) are optional, relationships (posts, comments) are optional, and I assign values when creating a new object, but Core Data still throws a nilError during registration; I have uploaded my project to GitHub for your reference here: https://github.com/Kawiichao/job. If reviewing it requires any payment, please let me know in advance. Thank you very much for your kind offer—I really appreciate it!

I have one target building and filling the SwiftData store and then copying the same store file to another target of the app to use the contents. That worked fine from iOS 17 to iOS 26.0.1 Under iOS 26.1 I am getting following error: CoreData: error: This store file was previously used on a build with Persistence-1522 but is now running on a build with Persistence-1518. file:///Users/xxx/Library/Developer/CoreSimulator/Devices/0FE92EA2-57FA-4A5E-ABD0-DAB4DABC3E02/data/Containers/Data/Application/B44D3256-9B09-4A60-94E2-C5F11A6519E7/Documents/default.store What does it mean and how to get back to working app under iOS 26.1?

I've understood that SwiftData is not abled to share the whole content of a cloudkit database. So I'm trying to rewrite everything. Does someone knows id Sharing is coming on SwiftData at WWDC 26? Anyway, can someone can point me an example a a configured coredata stack that share all its content with other icloud users (with sharing pane and accept invitation code). At this step, on the owner side, I see some data in the default zone of my private container but nothing is visible on the shared zone. Maybe I don't understand where and when I should check shared data in cloudkit console. Need Help also here. See below by configuration stack: // Core Data container public lazy var container: NSPersistentContainer = { switch delegate.usage() { case .preview : return previewContainer() case .local : return localContainer() case .cloudKit : return cloudKitContainer() } }() private func cloudKitContainer() -> NSPersistentContainer { let modelURL = delegate.modelURL() let modelName = modelURL.deletingPathExtension().lastPathComponent guard let model = NSManagedObjectModel(contentsOf: modelURL) else { fatalError("Could not load Core Data model from \(modelURL)") } let container = NSPersistentCloudKitContainer( name: modelName, managedObjectModel: model ) let groupIdentifier = AppManager.shared.groupIdentifier guard let appGroupURL = FileManager.default.containerURL ( forSecurityApplicationGroupIdentifier: groupIdentifier ) else { fatalError("App Group not found: \(groupIdentifier)") } // MARK: - Private Store Configuration let privateStoreURL = appGroupURL.appendingPathComponent("\(modelName).sqlite") let privateStoreDescription = NSPersistentStoreDescription(url: privateStoreURL) // Persistent history tracking (MANDATORY) privateStoreDescription.setOption(true as NSNumber, forKey: NSPersistentHistoryTrackingKey) privateStoreDescription.setOption(true as NSNumber, forKey: NSPersistentStoreRemoteChangeNotificationPostOptionKey) // CloudKit options for private database // Core Data automatically uses the default zone: com.apple.coredata.cloudkit.zone let privateCloudKitOptions = NSPersistentCloudKitContainerOptions(containerIdentifier: delegate.cloudKitIdentifier()) privateCloudKitOptions.databaseScope = .private privateStoreDescription.cloudKitContainerOptions = privateCloudKitOptions // MARK: - Shared Store Configuration guard let sharedStoreDescription = privateStoreDescription.copy() as? NSPersistentStoreDescription else { fatalError("Create shareDesc error") } // The shared store receives zones that others share with us via CloudKit's shared database sharedStoreDescription.url = appGroupURL.appendingPathComponent("\(modelName)-shared.sqlite") // Persistent history tracking (MANDATORY) sharedStoreDescription.setOption(true as NSNumber, forKey: NSPersistentHistoryTrackingKey) sharedStoreDescription.setOption(true as NSNumber, forKey: NSPersistentStoreRemoteChangeNotificationPostOptionKey) // CloudKit options for shared database // This syncs data from CloudKit shared zones when we accept share invitations let sharedCloudKitOptions = NSPersistentCloudKitContainerOptions(containerIdentifier: delegate.cloudKitIdentifier()) sharedCloudKitOptions.databaseScope = .shared sharedStoreDescription.cloudKitContainerOptions = sharedCloudKitOptions // Configure both stores // Private store: com.apple.coredata.cloudkit.zone in private database // Shared store: Receives shared zones we're invited to container.persistentStoreDescriptions = [privateStoreDescription, sharedStoreDescription] container.loadPersistentStores { storeDescription, error in if let error = error as NSError? { fatalError("DB init error:\(error.localizedDescription)") } else if let cloudKitContiainerOptions = storeDescription.cloudKitContainerOptions { switch cloudKitContiainerOptions.databaseScope { case .private: self._privatePersistentStore = container.persistentStoreCoordinator.persistentStore(for: privateStoreDescription.url!) case .shared: self._sharedPersistentStore = container.persistentStoreCoordinator.persistentStore(for: sharedStoreDescription.url!) default: break } } let scope = storeDescription.cloudKitContainerOptions?.databaseScope == .shared ? "shared" : "private" print("✅ \(scope) store loaded at: \(storeDescription.url?.path ?? "unknown")") } // Auto-merge container.viewContext.automaticallyMergesChangesFromParent = true container.viewContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy do { try container.viewContext.setQueryGenerationFrom(.current) } catch { fatalError("Fail to pin viewContext to the current generation:\(error)") } return container }