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?

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

I have an app that I signed and distribute between some internal testflight users. Potentially I want to invite some 'Public' beta testers which don't need to validate (_World have read rights in the public database) Question: Do I need to have a working public CloudKit , when users are invited through TestFlight, or are they going to test on the development container? I understand that when I invite beta-tester without authorization (external testers) they cannot access the developer container, so therefore I need to have the production CloudKit container up and running. I have tried to populate the public production container, but for whatever reason my upload app still goes to the development container. I have archived the app, and tried, but no luck. I let xcode manage my certificates/profiles. but what do I need to change to be able to use my upload file to upload the production container, instead of the development. I tried: init() { container = CKContainer(identifier: "iCloud.com.xxxx.xxxx") publicDB = container.publicCloudDatabase I got no error in the console, but data is always populated to the development database, instead the production. I tried to create a provisioning profile, but for some reason Xcode doesn't like it. Tried to create one a different provisioning profile manual through the developer portal, for the app. but xcode doesn't want to use that, and mentions that the requirement are already in place. What can I check/do to solve this.

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.

While testing record creation in public CloudKit database for authenticated user I am able to do so without any issues. But for devices missing iCloud account or authentication expired I am seeing the below error: ▿ <CKError 0x97a959200: "Permission Failure" (10/2007); server message = "CREATE operation not permitted"; op = 67331DE3AF3DD666; uuid = 1F3ACD4F-A799-4CD4-ADF0-EDE9E12F2DCB; container ID = "***"> _nsError : <CKError 0x97a959200: "Permission Failure" (10/2007); server message = "CREATE operation not permitted"; op = 67331DE3AF3DD666; uuid = 1F3ACD4F-A799-4CD4-ADF0-EDE9E12F2DCB; container ID = "***"> I am unable to add create/write permission to _world security role in dashboard. Is this something not supported by Cloudkit? Only authenticated iCloud users will be able to create and write data to public database as well?

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?

In the future, is there any plans to have AppMigrationKit for macOS-Windows cross transfers (or Linux, ChromeOS, HarmonyOS NEXT, etc)? Additionally, will the migration framework remain just iOS <-> Android or will it extend to Windows tablets, ChromeOS Tablets, HarmonyOS NEXT, KaiOS, Series 30+, Linux mobile, etc.

I am developing an app that uses CloudKit sharing. I recently upgraded my iPad to use 23A5336a. After that upgrade, I can no longer accept a share that is sent to me. I have rebooted the iPad and logged out of the iCloud account and logged back in. Every time I get a share link and tap it, it says: " The owner stopped sharing or your account (xxx) doesn't have permission to open it" This same code, running on the iOS26 device can share with device running iOS18. Is this a known defect? Anything I can do to help resolve this issue?

Here’s the situation: • You’re downloading a huge list of data from iCloud. • You’re saving it one by one (sequentially) into SwiftData. • You don’t want the SwiftUI view to refresh until all the data is imported. • After all the import is finished, SwiftUI should show the new data. The Problem If you insert into the same ModelContext that SwiftUI’s @Environment(.modelContext) is watching, each insert may cause SwiftUI to start reloading immediately. That will make the UI feel slow, and glitchy, because SwiftUI will keep trying to re-render while you’re still importing. How to achieve this in Swift Data ?

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?

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 }

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, 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.

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.

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!

Updated the phone to iOS 26.1 and now the app is not working anymore, even previously approved version published on App Store which works perfectly on iOS 26.0.1, and iOS 18+. I deleted the app from the phone and installed fresh from App Store, still the same. Logic is that on start app copies previously prepared SwiftData store file (using the same models) from app bundle to Documents directory and uses it. Currently app just hungs with loader spinner spinning as it can t connect to the store. Getting this error in console when running from Xcode on real device with iOS 26.1 installed: CoreData: error: CoreData: error: Store failed to load. <NSPersistentStoreDescription: 0x10c599e90> (type: SQLite, url: file:///var/mobile/Containers/Data/Application/DA32188D-8887-48F7-B828-1F676C8FBEF8/Documents/default.store) with error = Error Domain=NSCocoaErrorDomain Code=134140 "Persistent store migration failed, missing mapping model." UserInfo={sourceModel=(<NSManagedObjectModel: 0x10c503ac0>) isEditable 0, entities { /// there goes some long models description addPersistentStoreWithType:configuration:URL:options:error: returned error NSCocoaErrorDomain (134140) Any help or workaround will be 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.