I am implementing a custom migration, and facing an issue while implementing a WAL checkpointing. Here is the code for WAL checkpointing func forceWALCheckpointingForStore(at storeURL: URL, model: NSManagedObjectModel) throws { let persistentStoreCoordinator = NSPersistentStoreCoordinator(managedObjectModel: model) let options = [NSSQLitePragmasOption: ["journal_mode": "DELETE"]] let store = try persistentStoreCoordinator.addPersistentStore(type: .sqlite, at: storeURL, options: options) try persistentStoreCoordinator.remove(store) } When the coordinator tries to add the store I am getting the following error fault: Store opened without NSPersistentHistoryTrackingKey but previously had been opened with NSPersistentHistoryTrackingKey - Forcing into Read Only mode store My questions are Is it really necessary to force WAL checkpointing before migration? I am expecting NSMigrationManager to handle it internally. I am assuming this because the migrateStore function asks for the sourceType where I am passing StoreType.sqlite If checkpointing is required, then how do I address the original issue Note: Since my app supports macOS 13, I am not able to use the newly introduced Staged migrations. There is similar question on Stackoverflow that remains unanswered. https://stackoverflow.com/q/69131577/1311902

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?

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?

In my app, I've been using ModelActors in SwiftData, and using actors with a custom executor in Core Data to create concurrency safe services. I have multiple actor services that relate to different data model components or features, each that have their own internally managed state (DocumentService, ImportService, etc). The problem I've ran into, is that I need to be able to use multiple of these services within another service, and those services need to share the same context. Swift 6 doesn't allow passing contexts across actors. The specific problem I have is that I need a master service that makes multiple unrelated changes without saving them to the main context until approved by the user. I've tried to find a solution in SwiftData and Core Data, but both have the same problem which is contexts are not sendable. Read the comments in the code to see the issue: /// This actor does multiple things without saving, until committed in SwiftData. @ModelActor actor DatabaseHelper { func commitChange() throws { try modelContext.save() } func makeChanges() async throws { // Do unrelated expensive tasks on the child context... // Next, use our item service let service = ItemService(modelContainer: SwiftDataStack.shared.container) let id = try await service.expensiveBackgroundTask(saveChanges: false) // Now that we've used the service, we need to access something the service created. // However, because the service created its own context and it was never saved, we can't access it. let itemFromService = context.fetch(id) // fails // We need to be able to access changes made from the service within this service, /// so instead I tried to create the service by passing the current service context, however that results in: // ERROR: Sending 'self.modelContext' risks causing data races let serviceFromContext = ItemService(context: modelContext) // Swift Data doesn't let you create child contexts, so the same context must be used in order to change data without saving. } } @ModelActor actor ItemService { init(context: ModelContext) { modelContainer = SwiftDataStack.shared.container modelExecutor = DefaultSerialModelExecutor(modelContext: context) } func expensiveBackgroundTask(saveChanges: Bool = true) async throws -> PersistentIdentifier? { // Do something expensive... return nil } } Core Data has the same problem: /// This actor does multiple things without saving, until committed in Core Data. actor CoreDataHelper { let parentContext: NSManagedObjectContext let context: NSManagedObjectContext /// In Core Data, I can create a child context from a background context. /// This lets you modify the context and save it without updating the main context. init(progress: Progress = Progress()) { parentContext = CoreDataStack.shared.newBackgroundContext() let childContext = NSManagedObjectContext(concurrencyType: .privateQueueConcurrencyType) childContext.parent = parentContext self.context = childContext } /// To commit changes, save the parent context pushing them to the main context. func commitChange() async throws { // ERROR: Sending 'self.parentContext' risks causing data races try await parentContext.perform { try self.parentContext.save() } } func makeChanges() async throws { // Do unrelated expensive tasks on the child context... // As with the Swift Data example, I am unable to create a service that uses the current actors context from here. // ERROR: Sending 'self.context' risks causing data races let service = ItemService(context: self.context) } } Am I going about this wrong, or is there a solution to fix these errors? Some services are very large and have their own internal state. So it would be very difficult to merge all of them into a single service. I also am using Core Data, and SwiftData extensively so I need a solution for both. I seem to have trapped myself into a corner trying to make everything concurrency save, so any help would be appreciated!

I am using NSPersistentCloudKitContainer and I decided to add a property to an entity. I accidentally ran try! container.initializeCloudKitSchema(options: []) while using the production container in Xcode (com.apple.developer.icloud-container-environment) which throw a couple of errors and created some FAKE_ records in my production container. So I changed to my development container and ran the try! container.initializeCloudKitSchema(options: []) and now it succeeded. After that I cleaned up the FAKE_ records scattered in production container but in Xcode when I'm running I now get these logs in the console (and I can't seem to get rid of them): error: CoreData+CloudKit: -[NSCloudKitMirroringDelegate _importFinishedWithResult:importer:](1398): <PFCloudKitImporter: 0x300cc72c0>: Import failed with error: Error Domain=NSCocoaErrorDomain Code=4864 "*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x73, 0x61, 0x6d)" UserInfo={NSDebugDescription=*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x73, 0x61, 0x6d)} error: CoreData+CloudKit: -[NSCloudKitMirroringDelegate recoverFromError:](2310): <NSCloudKitMirroringDelegate: 0x302695770> - Attempting recovery from error: Error Domain=NSCocoaErrorDomain Code=4864 "*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x73, 0x61, 0x6d)" UserInfo={NSDebugDescription=*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x73, 0x61, 0x6d)} error: CoreData+CloudKit: -[NSCloudKitMirroringDelegate _recoverFromError:withZoneIDs:forStore:inMonitor:](2620): <NSCloudKitMirroringDelegate: 0x302695770> - Failed to recover from error: NSCocoaErrorDomain:4864 Recovery encountered the following error: (null):0 error: CoreData+CloudKit: -[NSCloudKitMirroringDelegate resetAfterError:andKeepContainer:](610): <NSCloudKitMirroringDelegate: 0x302695770> - resetting internal state after error: Error Domain=NSCocoaErrorDomain Code=4864 "*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x73, 0x61, 0x6d)" UserInfo={NSDebugDescription=*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x73, 0x61, 0x6d)} error: CoreData+CloudKit: -[NSCloudKitMirroringDelegate _requestAbortedNotInitialized:](2198): <NSCloudKitMirroringDelegate: 0x302695770> - Never successfully initialized and cannot execute request '<NSCloudKitMirroringExportRequest: 0x303a52d00> 548CB420-E378-42E5-9607-D23E7A2A364D' due to error: Error Domain=NSCocoaErrorDomain Code=4864 "*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x73, 0x61, 0x6d)" UserInfo={NSDebugDescription=*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x73, 0x61, 0x6d)}

Hi Folks, starting with iOS18 and using Xcode16, accessing fetchedProperties results in an error. I identified the issue to occur as soon as the initialization of a fetched property with external binary data storage starts. Console output during debugging: *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'This expression has evaluation disabled' *** First throw call stack: [...] libc++abi: terminating due to uncaught exception of type NSException Console output when trying to "print" the item via the contact menu of the debugger: Printing description of variable: error: error: Execution was interrupted, reason: internal ObjC exception breakpoint(-6).. The process has been returned to the state before expression evaluation. Message from debugger: killed The identical code works with iOS before iOS 18 (same for iPadOS 18). Does anyone observed a similar issue and figured out a solution already? Cheers, folox

I am running into some issues when trying to destroy CoreData persistentStores. When a user logs out of my app, I want to completely reset CoreData and delete any existing data. My code to reset CoreData looks like this: let coordinator = self.persistentContainer.persistentStoreCoordinator self.persistentContainer.viewContext.reset() coordinator.persistentStores.forEach { store in guard let url = store.url else { return } do { try coordinator.destroyPersistentStore(at: url, type: .sqlite) _ = try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url) } catch { print(error) } } However, my app is crashing with Object 0xb2b5cc80445813de <x-coredata://BDB999D4-49A4-4CB3-AC3A-666AD60BEFC6/AccountEntity/p5> persistent store is not reachable from this NSManagedObjectContext's coordinator It seems this is related to the SwiftUI @FetchRequest wrappers. If I do not open the views where I am using @FetchRequest, the logout goes smoothly. Otherwise, I get the crash above. Has anyone run into anything similar? Is there something else I need to do to get the underlying FRC to release its references to those entities? I was under the impression that calling reset() on the managed object context would be enough to remove those items from memory and get the destroying of the persistent store to go smoothly. Alternately, is there another/better way I should be destroying the DB? Any advice or related observations would be greatly appreciated. Thank you!

I am trying to migrate my Core Data model to a new version with a new attribute added to it. Since my app supports macOS 13 I am not able to use the newly introduced Staged migrations. After much digging I found that the app is not able to find the Mapping Model when one of the attribute has "Preserve after deletion" enabled. I have enabled migration debbuging using com.apple.CoreData.MigrationDebug 1 I am getting following error error: CoreData: error: (migration) migration failed with error Error Domain=NSCocoaErrorDomain Code=134140 "Persistent store migration failed, missing mapping model." What is the way out here?

I created a data structure based on a dictionary of words. The purpose is to link each word to all other words made up of the same letters plus one. Example: table -> ablate, cablet, tabled, gablet, albeit, albite, etc. For this I built a data model made of three entities: Word, Draw, Link. A Draw is a set of letters corresponding to a Word and sorted in alphabetic order, like : HOUSE -> EHOSU. A Link is a letter that you add to a Draw to get another Draw. So my data model looks like this: And here is how I implemented it in Xcode: Entity Word (let's forget the attribute optComp that plays no role here) Entity Draw Entity Link I am populating the data in two steps: first I read a list of words from a .txt source and I populate the Word entity and at the same time the Draw entity with the corresponding relationship (function loadDic()) This first step apparently works fine. I can easily find all anagrams of any word with something like word.sort.word.spelling I read through the Draw entity. For each draw I seek all existing +1 draws considering each letter of the alphabet. If there are, I create a Link and add the relationships (function createLinks()) Here is where something goes wrong. If the Link's and the relationship Draw.plus seem to be correctly created, the other relationship Link.gives is only partially populated, say 50%. Moreover, I tried to apply an additional routine (updateLinks()) , focusing only on Link's with an empty Link.gives relationship and updating them. But again, only 50% of the nil relationships appear to be populated. I could not find out why those relationships are not properly populated. If someone can help me out I would be grateful. Here is the code: LoadDic() function (OK) : func loadDic() { print("Loading dictionary...") dataAlreadyLoaded.toggle() guard let url = Bundle.main.url(forResource: INPUT_FILE, withExtension: "txt") else { fatalError("\(INPUT_FILE).txt not found") } if let dico = try? String(contentsOf: url, encoding: String.Encoding.utf8 ) { let lines = dico.split(separator: "\r\n") for line in lines { let lineArray = line.split(separator: " ") print("\(lineArray[0])") // word let wordSorted = String(lineArray[0].sorted()) let draw = getDraw(drawLetters: wordSorted) ?? addDraw(drawLetters: wordSorted) // look if draw already exists, otherwise create new one. let wordItem = Word(context: viewContext) // create word entry with to-one-relationship to draw wordItem.spelling = String(lineArray[0]) wordItem.optComp = (Int(String(lineArray[1])) == 1) wordItem.sort = draw do { try viewContext.save() } catch { print("Errort saving ods9: \(error)") } } } print("Ods Chargé") } func addDraw(drawLetters: String) -> Draw { let newDraw = Draw(context: viewContext) newDraw.draw = drawLetters return(newDraw) } func getDraw(drawLetters: String) -> Draw? { let request: NSFetchRequest<Draw> = Draw.fetchRequest() request.entity = Draw.entity() request.predicate = NSPredicate(format: "draw == %@", drawLetters) do { let drw = try viewContext.fetch(request) return drw.isEmpty ? nil : drw[0] } catch { print("Erreur recherche Tirage") return nil } } createLinks() function (NOK): func createLinks() { var erreur = " fetch request <Draw>" let request: NSFetchRequest<Draw> = Draw.fetchRequest() request.entity = Draw.entity() request.predicate = NSPredicate(value: true) print("Building relationships...") do { let draws = try viewContext.fetch(request) count = draws.count for draw in draws { print("\(count) - \(draw.draw!)") linkTable.removeAll() for letter in ALPHABET { print(letter) let drawLettersPlus = String((draw.draw! + String(letter)).sorted()) // draw with one more letter if let drawPlus = draws.first(where: { $0.draw == drawLettersPlus }) { // look for Draw entity that matches augmented draw let linkItem = Link(context: viewContext) // if found, create new link based on letter with relationship to augmented draw linkItem.letter = String(letter) linkItem.gives = drawPlus erreur = " saving \(draw.draw!) + \(letter)" try viewContext.save() linkTable.append(linkItem) // saves link to populate the one-to-many relationship of the initial draw, once the alphabet is through } } let drawUpdate = draw as NSManagedObject // populate the one-to-many relationship of the initial draw let linkSet = Set(linkTable) as NSSet drawUpdate.setValue(linkSet, forKey: "plus") erreur = " saving \(draw.draw!) links plus" try viewContext.save() count -= 1 // next draw } } catch { print("Error " + erreur) } print("Graph completed") } updateLinks function (NOK): func updateLinks() { var erreur = "fetch request <Link>" let request: NSFetchRequest<Link> = Link.fetchRequest() request.entity = Link.entity() print("Running patch...") do { request.predicate = NSPredicate(format: "gives == nil") let links = try viewContext.fetch(request) for link in links { let baseDraw = link.back!.draw! print("\(baseDraw) \(link.letter!)") let augmDrawLetters = String((baseDraw + link.letter!).sorted()) if let augmDraw = getDraw(drawLetters: augmDrawLetters) { viewContext.perform { let updateLink = link as NSManagedObject updateLink.setValue(augmDraw, forKey: "gives") erreur = " saving \(augmDraw.draw!) \(link.letter!)" do { try viewContext.save() } catch { print("Erreur mise à jour lien") } } } } } catch { print("Error " + erreur) } } RESULT And this is the output showing the content of the Draw entity with relationships after createLinks() is applied: And here after updateLinks() is applied :

I'm experiencing a crash during a lightweight Core Data migration when a widget that accesses the same database is installed. The migration fails with the following error: CoreData: error: addPersistentStoreWithType:configuration:URL:options:error: returned error NSCocoaErrorDomain (134100) error: userInfo: CoreData: error: userInfo: error: metadata : { NSPersistenceFrameworkVersion = 1414; NSStoreModelVersionChecksumKey = "dY78fBnnOm7gYtb+QT14GVGuEmVlvFSYrb9lWAOMCTs="; NSStoreModelVersionHashes = { Entity1 = { ... }; Entity2 = { ... }; Entity3 = { ... }; Entity4 = { ... }; Entity5 = { ... }; }; NSStoreModelVersionHashesDigest = "aOalpc6zSzr/VpduXuWLT8MLQFxSY4kHlBo/nuX0TVQ/EZ+MJ8ye76KYeSfmZStM38VkyeyiIPf4XHQTMZiH5g=="; NSStoreModelVersionHashesVersion = 3; NSStoreModelVersionIdentifiers = ( "" ); NSStoreType = SQLite; NSStoreUUID = "9AAA7AB7-18D4-4DE4-9B54-893D08FA7FC4"; "_NSAutoVacuumLevel" = 2; } The issue occurs only when the widget is installed. If I remove the widget’s access to the Core Data store, the migration completes successfully. The crash happens only once—after the app is restarted, everything works fine. This occurs even though I'm using lightweight migration, which should not require manual intervention. My suspicion is that simultaneous access to the Core Data store by both the main app and the widget during migration might be causing the issue. Has anyone encountered a similar issue? Is there a recommended way to ensure safe migration while still allowing the widget to access Core Data? Any insights or recommendations would be greatly appreciated.

I'm calling a method with the context as parameter, within the context's perform block – is this really not legal in Swift 6? actor MyActor { func bar(context: NSManagedObjectContext) { /* some code */ } func foo(context: NSManagedObjectContext) { context.performAndWait { self.bar(context: context) // WARN: Sending 'context' risks causing data races; this is an error in the Swift 6 language mode // 'self'-isolated 'context' is captured by a actor-isolated closure. actor-isolated uses in closure may race against later nonisolated uses // Access can happen concurrently } } } The warning appears when I call a method with a context parameter, within the performAndWait-block. Background: In my app I have methods that takes in API data, and I need to call the same methods from multiple places with the same context to store it, and I do not want to copy paste the code and have hundreds of lines of duplicate code. Is there a well-known "this is how you should do it" for situations like this? This is related to a previous post I made, but it's a bit flimsy and got no response: https://developer.apple.com/forums/thread/770605

I'm having some issues where only a subset of records appear in CloudKit dashboard after I have saved some records in my iOS app using NSPersistentCloudKitContainer. I have noticed that when I'm running my app using the development environment of my CloudKit container everything works smoothly and is uploaded as expected but when I'm using the production environment only a subset of records are actually uploaded. I'm pulling my hair on how to debug this. -com.apple.CoreData.CloudKitDebug and -com.apple.CoreData.SQLDebug pukes out too much info in the console for me to pinpoint any issue.

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 am trying to add a custom policy to Entity Mapping and it refuses to work because the app name has a space in it. I tried replacing the space character with underscore and hyphen but it still does not work. I tried creating an MVP where app name did not have any space and it worked in the first try. However, for another MVP where app name had a space in it, it is not working at all.

Hello, I'm using CoreData + CloudKit and I am facing the following error 134100 "The managed object model version used to open the persistent store is incompatible with the one that was used to create the persistent store." All my schema updates are composed of adding optional attributes to existing entities, adding non-optional attributes (with default value) to existing entities or adding new entities Basically, only things that lightweight migrations can handle. Every time I update the schema, I add a new model version of xcdatamodel - who only has a single configuration (the "Default" one). And I also deploy the updated CloudKit schema from the dashboard. It worked up to v3 of my xcdatamodel, but started to crash for a few users at v4 when I added 16 new attributes (in total) to 4 existing entities. Then again at v5 when I added 2 new optional attributes to 1 existing entity. I'm using a singleton and here is the code: private func generateCloudKitContainer() -> NSPersistentCloudKitContainer { let container = NSPersistentCloudKitContainer(name: "MyAppModel") let fileLocation = URL(...) let description = NSPersistentStoreDescription(url: fileLocation) description.shouldMigrateStoreAutomatically = true description.setOption(true as NSNumber, forKey: NSPersistentHistoryTrackingKey) description.setOption(true as NSNumber, forKey: NSPersistentStoreRemoteChangeNotificationPostOptionKey) let options = NSPersistentCloudKitContainerOptions(containerIdentifier: "iCloud.com.company.MyApp") options.databaseScope = .private description.cloudKitContainerOptions = options container.persistentStoreDescriptions = [description] container.viewContext.automaticallyMergesChangesFromParent = true container.loadPersistentStores { description, error in container.viewContext.mergePolicy = NSMergePolicy(merge: .mergeByPropertyObjectTrumpMergePolicyType) if let error { // Error happens here! } } return container } I can't reproduce it yet. I don't really understand what could lead to this error.

I've noticed several crashes that look like they're caused by an index out of bound in internal methods of NSFetchedResultsController. This happens while changes are merged from the persistent store container into the view context. Here's an example of the last exception backtrace. Exactly which internal methods that are called in - [NSFetchedResultsController(PrivateMethods) _core_managedObjectContextDidChange:] vary between crash reports but they all end up crashing from _NSArrayRaiseBoundException. The Core Data stack consists of one persistent store, one persistent store coordinator that the view context is set up to automatically merge changes from, and data is saved to disk from background context. persistentContainer.loadPersistentStores(...) viewContext = persistentContainer.viewContext viewContext.automaticallyMergesChangesFromParent = true backgroundContext = persistentContainer.newBackgroundContext() backgroundContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy backgroundClientContext = persistentContainer.newBackgroundContext() backgroundClientContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy Does anyone have any ideas what could be causing this? Thankful for any ideas or advice on how to investigate further.

Hi, This issue started with iOS 18, in iOS 17 it worked correctly. I think there was a change in SectionedFetchRequest so maybe I missed it but it did work in iOS 17. I have a List that uses SectionedFetchRequest to show entries from CoreData. The setup is like this: struct ManageBooksView: View { @SectionedFetchRequest<Int16, MyBooks>( sectionIdentifier: \.groupType, sortDescriptors: [SortDescriptor(\.groupType), SortDescriptor(\.name)] ) private var books: SectionedFetchResults<Int16, MyBooks> var body: some View { NavigationStack { List { ForEach(books) { section in Section(header: Text(section.id)) { ForEach(section) { book in NavigationLink { EditView(book: book) } label: { Text(book.name) } } } } } .listStyle(.insetGrouped) } } } struct EditView: View { private var book: MyBooks init(book: MyBooks) { print("Init hit") self.book = book } } Test 1: So now when I change name of the Book entity inside the EditView and do save on the view context and go back, the custom EditView is correctly hit again. Test 2: If I do the same changes on a different attribute of the Book entity the custom init of EditView is not hit and it is stuck with the initial result from SectionedFetchResults. I also noticed that if I remove SortDescriptor(\.name) from the sortDescriptors and do Test 1, it not longer works even for name, so it looks like the only "observed" change is on the attributes inside sortDescriptors. Any suggestions will be helpful, thank you.

I'm using NSPersistentCloudKitContainer to save, edit, and delete items, but it only works half of the time. When I delete an item and terminate the app and repoen, sometimes the item is still there and sometimes it isn't. The operations are simple enough: moc.delete(thing) try? moc.save() Here is my DataController. I'm happy to provide more info as needed class DataController: ObservableObject { let container: NSPersistentCloudKitContainer @Published var moc: NSManagedObjectContext init() { container = NSPersistentCloudKitContainer(name: "AppName") container.loadPersistentStores { description, error in if let error = error { print("Core Data failed to load: \(error.localizedDescription)") } } #if DEBUG do { try container.initializeCloudKitSchema(options: []) } catch { print("Error initializing CloudKit schema: \(error.localizedDescription)") } #endif moc = container.viewContext } }

I followed these two resources and setup history tracking in SwiftData. SwiftData History tracking: Track model changes with SwiftData history For data deduplication: Sharing Core Data objects between iCloud users In the sample app (CoreDataCloudKitShare), a uuid: UUID field is used for deduplication logic. It sorts the entities by their uuids, reserves the first one, and marks the others as deduplicated. Would it be a viable solution to use a createdAt: Date field for the sort operation instead of a uuid field, or are dates inherently problematic?

I am currently building a screen time app and I am trying to figure out how to persist the family activity picker so that when my app closes and re-opens, the app selections in it are saved. I've successfully implemented core data and figured out how to store names of the selected apps in a list like this - Core Data addApp Function - func addApp(name: String, context: NSManagedObjectContext){ let newApp = AppToken(context: context) newApp.bundleIdentifier = name saveData(context: context) } Adding app selections to Core Data (after the family activity picker has updated the selection) - .onChange(of: model.selectionToDiscourage) { for i in model.selectionToDiscourage.applications { print(i) dataController.addApp(name:i.localizedDisplayName ?? "Temp", context: moc) } Printing saved selections in a list (bundleIdentifier is my attribute for my appToken entity, but I am just pulling the names here. For whatever reason all of them end up being Temp" as shown above anyway. In other words name:i.localizedDisplayName is not working and Temp is shown in the list for every app chosen) - if dataController.savedSelection.isEmpty { Text("No Apps Selected") .foregroundColor(.gray) } else { List(dataController.savedSelection, id: \.self) { app in Text(app.bundleIdentifier ?? "Unknown App") } .scrollContentBackground(.hidden) } So, when my app closes and reopens, the list of app names persists. Now, my issue is figuring out how to write back to selectionToDiscourage and loading the family activity picker with those saved apps. I have no idea if I should be doing this a different way and if using Core Data is overkill, but I cannot figure out how it's syntactically possible to write back to this family activity picker when the app reopens - .familyActivityPicker(isPresented: $isPresented, selection:$model.selectionToDiscourage) Thank you to whoever takes a look at this!!