Hello, I recently published an app that uses Swift Data as its primary data storage. The app uses concurrency, background threads, async await, and BLE communication. Sadly, I see my app incurs many fringe crashes, involving EXC_BAD_ACCESS, KERN_INVALID_ADDRESS, EXC_BREAKPOINT, etc. I followed these guidelines: One ModelContainer that is stored as a global variable and used throughout. ModelContexts are created separately for each task, changes are saved manually, and models are not passed around. Threads with different ModelContexts might manipulate and/or read the same data simultaneously. I was under the impression this meets the usage requirements. I suspect perhaps the issue lies in my usage of contexts in a single await function, that might be paused and resumed on a different thread (although same execution path). Is that the case? If so, how should SwiftData be used in async scopes? Is there anything else particularly wrong in my approach?

Here is what I thought I want to give each user a unique container, when the user login or register, the user could isolate their data in specific container. I shared the container in a singleton actor, I found it's possible to update the container in that actor. But I think it won't affect the modelContext which is in the Environment. Does SwiftData allow me or recommend to do that?

Apple WTF? What did you do to all my Apps? none of them work in iOS26.1 (all worked in 26.0). XCode simply says: CoreData: error: addPersistentStoreWithType:configuration:URL:options:error: returned error NSCocoaErrorDomain (134140) * SwiftData is supposed to do all these automatically 🤷🏻

DESCRIPTION I have an App use iCloud to save data. The App had a CoreData ManagedObject 'Product', 'Product' Object had an attribute name 'count' and it is a Double Type. I need to synchronises 'count' property across multiple devices. for example: I have a devices A、B. A device set 'Product.count' = 100. B device set 'Product.count' = 50. I hope the 'Product.count' == 150 that results. how to synchronises the 'Product.count' == 150 for multiple devices. If I have more devices in future, How to get the latest 'Product.count' that it is correct result.

I have implemented CKSyncEngine synchronization, and it works well. I can update data on one device and see the changes propagate to another device quickly. However, the initial sync when a user downloads the app on a new device is a significant issue for both me and my users. One problem is that the sync engine fetches deletion events from the server. On a new device, the local database is empty, so these deletions are essentially no-ops. This would not be a big problem if there were only a few records or if it was fast. I measured the initial sync and found that there are 150 modified records and 62,168 deletions. Counting these alone takes over five minutes, even without processing them. The deletions do nothing because the local database has nothing to delete, yet they still add a significant delay. I understand that the sync engine ensures consistency across all devices, but five minutes of waiting with the app open just to insert a small number of records is excessive. The problem would be worse if there were tens of thousands of new records to insert, since downloading and saving the data would take even longer. This leads to a poor user experience. Users open the app and see data being populated for several minutes, or they are stuck on a screen that says the data is being synchronized with iCloud. I am wondering if there is a way to make the sync engine ignore deletion events when the state serialization is nil. Alternatively, is there a recommended method for handling initial synchronization more efficiently? One idea I considered is storing all the data as a backup in iCloud Documents, along with the state serialization at that point in time. When a user opens the app for the first time, I could download the file, extract the data, and set the state serialization to the saved value. I am not sure if this would work. I do not know if state serialization is tied to the device or if it only represents the point where the sync engine left off. My guess is that it might reference some local device storage. I am not sure what else to try. I could fetch all data using CloudKit, create the sync engine with an empty state serialization, and let it fetch everything again, but that would still take a long time. My records are very small, mostly a date when something happened and an ID referencing the parent. Since the app tracks watched episodes, I only store the date the user watched the episode and the ID of that episode.

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!

I have an issue in my app, where the crashing frame is an assertionFailure in BackingData.set inside SwiftData framework. My own app doesn't appear until frame 14. I have no idea what causes this, or even how to create a reproducible project as this only happens on some devices. The frame prior to the assertionFailure is this: #1 (null) in BackingData.set(any:value:) () It seems like there is a backing data encoding happening in my Model class, and some value is causing it to fail. The model being accessed is through a relationship, and the frame in the app crashing is along the lines of Text(parent.child.name) Obviously, something is wrong in how I have made child, but the part that stand out to me is the assertionFailure in a release build

After Xcode 26.1 was updated and installing the OS 26.1 simulators, my app started crashing related to transformable properties. When I checked my schema, I noticed that properties with array collection types are suddenly set with an option transformable with Optional("NSSecureUnarchiveFromData")], even though I do not use any transformable types. I verified the macros, no transformable was specified. This is causing ModelCoders to encode/decode my properties incorrectly. This is not an issue when I switch back to OS 26.0 simulators.

Some users of my app are reporting total loss of data while using the app. This is happening specifically when they enable iCloud sync. I am doing following private func setupContainer(enableICloud: Bool) { container = NSPersistentCloudKitContainer(name: "") container.viewContext.automaticallyMergesChangesFromParent = true container.viewContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy guard let description: NSPersistentStoreDescription = container.persistentStoreDescriptions.first else { fatalError() } description.setOption(true as NSNumber, forKey: NSPersistentHistoryTrackingKey) description.setOption(true as NSNumber, forKey: NSPersistentStoreRemoteChangeNotificationPostOptionKey) if enableICloud == false { description.cloudKitContainerOptions = nil } container.loadPersistentStores { description, error in if let error { // Handle error } } } When user clicks on Toggle to enable/disable iCloud sync I just set the description.cloudKitContainerOptions to nil and then user is asked to restart the app. Apart from that I periodically run the clear history func deleteTransactionHistory() { let sevenDaysAgo = Calendar.current.date(byAdding: .day, value: -7, to: Date())! let purgeHistoryRequest = NSPersistentHistoryChangeRequest.deleteHistory(before: sevenDaysAgo) let backgroundContext = container.newBackgroundContext() backgroundContext.performAndWait { try! backgroundContext.execute(purgeHistoryRequest) } }

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)) } } } }

I have a model with a FamilyActivitySelection, currently i'm using a codable struct to store it with UserDefaults, but would prefer strongly to transition to Swift Data

I have a new app I am working on, it uses, a container id like com.me.mycompany.FancyApp.prod, the description in the app is My Fancy App. When I deploy the app via TestFlight on a real device, the sync seems to work, but when I view iCloud->Storage-List, I see my app icon, and the name "prod". Where did the name prod come from? It should be My Fancy App, which is the actual name of the App.

Hello there, I have a problem reaching the CloudKit dashboard. Every time I login, the login successes but then I get the error: An error has caused this web page to stop working correctly. This also happens when I click on the Button CloudKit dashboard. Then I can reload the page, but the same errors occurs again and again. Can someone help me with this problem? Thank you very much

My project is using swiftData and I want to implement iCloud sync in it. Now, my data base doesnt have any optional attributes or relationships and CloudKit wants them to be optional. So, rather than editing all code with unwrapping code for the optionals, how can I provide a bridge that does so in the last stage of actually saving to the store? Sort of, capture it in a proxy object before writing and after reading from the store. Is there a neat way that can save a lot of debugging? I have code snippets from chat gpt and they are hard to debug. This is my first project in swiftUI. Thanks. Neerav

I implemented the cloudkit function, where users can connect with each other. The problem is, that if User A is doing a friend request and User B is accepting the request. The friend entry is correct visible for User B but not for User A. I can see in cloud kit that after the accepted request, the friend connection is set up correctly, also with the correct userID, but it not showing up for User A (the one that send the request)

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?

I am using cloudkit to save users high scores in a public database. The preference over using Game Center is because of simplicity and works really well for what I want to achieve. I simply want to let users know their global position. Because of data privacy laws the app asks the user for their permission to submit their score each time they get a new high score. However, I have noticed that CKRecords under 'created' and 'modified' in addition to UTC time and date also contain creatorUserRecordID. Could this be a privacy issue? Can you extract any personal information from this? Can this be used to track back to the user? Is it linked to CKUserIdentity which I understand does contain personal information, although as I understand you need users consent to get this information. Under creatorUserRecordID it says... "Every user of the app has a unique user record that is empty by default. Apps can add data to the user record on behalf of the user, but don’t store sensitive data in it" Currently I simply ask the user if they are happy to submit their score. But do I need to point out that it also stores a creatorUserRecordID? Obviously I don't want to do this if it is not needed as the user will 1) Probably not understand what a creatorUserRecordID is and 2) It makes the question complicated and will likely make most people refuse to submit their score. If it is a privacy issue, is there anyway to stop a CKRecord creating this ID and simply save a score? All I need is a list of scores so the app can determine their current position. If creatorUserRecordID does not contain any personal details and cannot be tracked back to the user please let me know, so I can be reassured that my current set up is fine and I am not causing any privacy issues! This post did seem to indicate you may possibly be able to fetch personal details?? https://stackoverflow.com/questions/55782166/how-do-i-fetch-any-info-about-user-that-modified-ckrecord

Hi Developer Community, I'm experiencing a critical issue with CloudKit schema deployment that's blocking my app release. I've been trying to resolve this for several days and would appreciate any assistance from the community or Apple engineers. Issue Description I'm unable to deploy my CloudKit schema from development to production environment. When attempting to deploy through the CloudKit Dashboard, I either get an "Internal Error" message or the deployment button is disabled. Environment Details App: Reef Trak (Reef aquarium tracking app) CloudKit Container: ************ Development Environment: Schema fully defined and working correctly Production Environment: No schema deployed (confirmed in dashboard) What I've Tried Using the "Deploy Schema to Production" button in CloudKit Dashboard (results in "Internal Error") Exporting schema from development and importing to production (fails) Using CloudKit CLI tools with API token (results in "invalid-scope" errors) Waiting 24-48 hours between attempts in case of propagation delays Current Status App works perfectly in development environment (when run from Xcode) In TestFlight/sideloaded builds (production environment), the app attempts to fetch records but fails with "Did not find record type: Tank" errors Log snippet showing the issue: [2025-03-21] [CloudKit] Schema creation failed: Error saving record <CKRecordID: 0x******; recordName=SchemaSetup_Tank_-**---****, zoneID=_defaultZone:defaultOwner> to server: Cannot create new type Tank in production schema [2025-03-21] [CloudKit] Failed to create schema for Tank after 3 attempts [2025-03-21] [CloudKit] Error creating schema for Tank: Error saving record <CKRecordID: 0x****; recordName=SchemaSetup_Tank_---**-**********, zoneID=_defaultZone:defaultOwner> to server: Cannot create new type Tank in production schema App Architecture & Critical Impact My app "Reef Trak" is built around a core data model where the "Tank" entity serves as the foundational element of the entire application architecture. The Tank entity is not just another data type - it's the primary container that establishes the hierarchical relationship for all other entities: All parameter measurements (pH, temperature, salinity, etc.) are associated with specific tanks All maintenance tasks and schedules are tank-specific All livestock (fish, corals, invertebrates) exist within the context of a tank All user achievements and progress tracking depend on tank-related activities Without the Tank schema being properly deployed to production, users experience what appears to be a completely empty application, despite successful authentication and CloudKit connection. The app shows "Successfully retrieved iCloud data" but displays no content because: The Tank record type doesn't exist in production Without Tanks, all child entities (even if their schemas existed) have no parent to associate with This creates a cascading failure where no data can be displayed or saved This issue effectively renders the entire application non-functional in production, despite working flawlessly in development. Users are left with an empty shell of an app that cannot fulfill its core purpose of reef tank management and monitoring. The inability to deploy the Tank schema to production is therefore not just a minor inconvenience but a complete blocker for the app's release and functionality. Questions Is there an alternative method to deploy schema to production that I'm missing? Could there be an issue with my account permissions or container configuration? Are there known issues with the CloudKit Dashboard deployment functionality? What's the recommended approach when the dashboard deployment fails? I've also submitted a Technical Support Incident, but I'm hoping to get this resolved quickly as it's blocking my App Store release. Thank you for any assistance!

Hello ! I am using this iCloud key value pair mechanism to save small app configuration between iOS and tvOS. I would say it is working. But when I go back and forth between debug and release (TestFlight) modes, it is like both apps are not connected anymore. I spend a lot of time restarting all devices, rebuilding, activating / deactivating iCloud capabilities in the Xcode project. It is like the app is mixing debug and release data. Is there an easy way to check what is happening exactly ? I know there's nothing on CloudKit console, so .... Thank you Frederic

Hi, Before the iOS 17.2 update the saving behavior of SwiftData was very straightforward, by default it saves to persistence storage and can be configured to save in memory only. Now it saves to memory by default and to make it save to persistence storage we need to use modelContext.Save(). But if we don't quit the App the changes will be saved after a while to persistence storage even without running modelContext.Save() ! How confusing can that be for both developer and the user ! Am I missing something here ? -- Kind Regards