We have an unreleased SwiftData app for iOS18+. While we were testing I saw reports on the forum about unexpected database migrations for codable arrays on iOS26.1. I'd like to ask a couple of questions: 1- Does this issue originate from the new Xcode version, or is it specific to iOS 26.1? 2- Is it possible to change our attribute so that users on older iOS versions receive the same model, preventing a migration from being triggered when they upgrade to iOS 26.1? One of our models looks like this: struct Point: Codable, Hashable { let x: Int let y: Int } @Model class Grid { private(set) var gridId: String = "" var points: [Point] = [] var updatedAt: Date = Date() private(set) var createdAt: Date = Date() #Index<Grid>([\.gridId]) ... } I can think of some options like: // 1 @Attribute(.transformable(by: CustomJsonTransformer.self)) var points: [Point] = [] // 2 @Attribute(.externalStorage) var points: [Point] = [] // 3 var points: Data = Data() // store points as data However, I'm not sure which one to use. What would you recommend to handle this, or is there a better strategy you would suggest?

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.

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

I've run into a strange issue. If a sheet loads a view that has a SwiftData @Query, and there is an if statement in the view body, I get the following error when running an iOS targetted SwiftUI app under MacOS 26.1: Set a .modelContext in view's environment to use Query While the view actually ends up loading the correct data, before it does, it ends up re-creating the sqlite store (opening as /dev/null). The strange thing is that this only happens if there is an if statement in the body. The statement need not ever evaluate true, but it causes the issue. Here's an example. It's based on the default xcode new iOS project w/ SwiftData: struct ContentView: View { @State private var isShowingSheet = false var body: some View { Button(action: { isShowingSheet.toggle() }) { Text("Show Sheet") } .sheet(isPresented: $isShowingSheet, onDismiss: didDismiss) { VStack { ContentSheetView() } } } func didDismiss() { } } struct ContentSheetView: View { @Environment(\.modelContext) private var modelContext @Query public var items: [Item] @State var fault: Bool = false var body: some View { VStack { if fault { Text("Fault!") } Button(action: addItem) { Label("Add Item", systemImage: "plus") } List { ForEach(items) { item in Text(item.timestamp, format: Date.FormatStyle(date: .numeric, time: .standard)) } } } } private func addItem() { withAnimation { let newItem = Item(timestamp: Date()) modelContext.insert(newItem) } } } It requires some data to be added to trigger, but after adding it and dismissing the sheet, opening up the sheet with trigger the Set a .modelContext in view's environment to use Query. Flipping on -com.apple.CoreData.SQLDebug 1 will show it trying to recreate the database. If you remove the if fault { Text("Fault!") } line, it goes away. It also doesn't appear to happen on iPhones or in the iPhone simulator. Explicitly passing modelContext to the ContentSheetView like ContentSheetView().modelContext(modelContext) also seems to fix it. Is this behavior expected?

Hello 👋, I encounter the "This model instance was invalidated because its backing data could no longer be found the store" crash with SwiftData. Which from what I understood means I try to access a model after it has been removed from the store (makes sense). I made a quick sample to reproduce/better understand because there some case(s) I can't figure it out. Let's take a concrete example, we have Home model and a Home can have many Room(s). // Sample code @MainActor let foo = Foo() // A single reference let database = Database(modelContainer: sharedModelContainer) // A single reference @MainActor class Foo { // Properties to explicilty keep reference of model(s) for the purpose of the POC var _homes = [Home]() var _rooms = [Room]() func fetch() async { let homes = await database.fetch().map { sharedModelContainer.mainContext.model(for: $0) as! Home } print(ObjectIdentifier(homes[0]), homes[0].rooms?.map(\.id)) // This will crash here or not. } // Same version of a delete function with subtle changes. // Depending on the one you use calling delete then fetch will result in a crash or not. // Keep a reference to only homes == NO CRASH func deleteV1() async { self._homes = await database.fetch().map { sharedModelContainer.mainContext.model(for: $0) as! Home } await database.delete() } // Keep a reference to only rooms == NO CRASH func deleteV2() async { self._rooms = await database.fetch().map { sharedModelContainer.mainContext.model(for: $0) as! Home }[0].rooms ?? [] await database.delete() } // Keep a reference to homes & rooms == CRASH 💥 func deleteV3() async { self._homes = await database.fetch().map { sharedModelContainer.mainContext.model(for: $0) as! Home } self._rooms = _homes[0].rooms ?? [] // or even only retain reference to rooms that have NOT been deleted 🤔 like here "id: 2" make it crash // self._rooms = _homes[0].rooms?.filter { r in r.id == "2" } ?? [] await database.delete() } } Calling deleteV() then fetch() will result in a crash or not depending on the scenario. I guess I understand deleteV1, deleteV2. In those case an unsaved model is served by the model(for:) API and accessing properties later on will resolve correctly. The doc says: "The identified persistent model, if known to the context; otherwise, an unsaved model with its persistentModelID property set to persistentModelID." But I'm not sure about deleteV3. It seems the ModelContext is kind of "aware" there is still cyclic reference between my models that are retained in my code so it will serve these instances instead when calling model(for:) API ? I see my home still have 4 rooms (instead of 2). So I then try to access rooms that are deleted and it crash. Why of that ? I mean why not returning home with two room like in deleteV1 ? Because SwiftData heavily rely on CoreData may be I miss a very simple thing here. If someone read this and have a clue for me I would be extremely graceful. PS: If someone wants to run it on his machine here's some helpful code: // Database let sharedModelContainer: ModelContainer = { let schema = Schema([ Home.self, Room.self, ]) let modelConfiguration = ModelConfiguration(schema: schema, isStoredInMemoryOnly: false) debugPrint(modelConfiguration.url.absoluteString.replacing("%20", with: "\\ ")) return try! ModelContainer(for: schema, configurations: [modelConfiguration]) }() extension Database { static let shared = Database(modelContainer: sharedModelContainer) } @ModelActor actor Database { func insert() async { let r1 = Room(id: "1", name: "R1") let r2 = Room(id: "2", name: "R2") let r3 = Room(id: "3", name: "R3") let r4 = Room(id: "4", name: "R4") let home = Home(id: "1", name: "My Home") home.rooms = [r1, r2, r3, r4] modelContext.insert(home) try! modelContext.save() } func fetch() async -> [PersistentIdentifier] { try! modelContext.fetchIdentifiers(FetchDescriptor<Home>()) } @MainActor func delete() async { let mainContext = sharedModelContainer.mainContext try! mainContext.delete( model: Room.self, where: #Predicate { r in r.id == "1" || r.id == "4" } ) try! mainContext.save() // 🤔 Calling fetch here seems to solve crash too, force home relationship to be rebuild correctly ? // let _ = try! sharedModelContainer.mainContext.fetch(FetchDescriptor<Home>()) } } // Models @Model class Home: Identifiable { @Attribute(.unique) public var id: String var name: String @Relationship(deleteRule: .cascade, inverse: \Room.home) var rooms: [Room]? init(id: String, name: String, rooms: [Room]? = nil) { self.id = id self.name = name self.rooms = rooms } } @Model class Room: Identifiable { @Attribute(.unique) public var id: String var name: String var home: Home? init(id: String, name: String, home: Home? = nil) { self.id = id self.name = name self.home = home } }

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.

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 🤷🏻

Hi all... The app I'm building is not really a beginner level test app, it's intended to be published so I want everything to be done properly while I'm both learning and building the app. I'm new to swift ecosystem but well experienced with python and JS ecosystems. These two models are causing my app to crash @Model final class CustomerModel { var id: String = UUID().uuidString var name: String = "" var email: String = "" var phone: String = "" var address: String = "" var city: String = "" var postalCode: String = "" var country: String = "" @Relationship(deleteRule: .nullify) var orders: [OrderModel]? @Relationship(deleteRule: .nullify) var invoices: [InvoiceModel]? init() {} } @Model final class OrderModel { var id: String = UUID().uuidString var total: Double = 0 var status: String = "processing" var tracking_id: String = "" var order_date: Date = Date.now var updated: Date = Date.now var delivery_date: Date? var active: Bool = true var createdAt: Date = Date.now var items: [OrderItem]? @Relationship(deleteRule: .nullify) var invoice: InvoiceModel? @Relationship(deleteRule: .nullify) var customer: CustomerModel? init() {} } both referenced in this model: @Model final class InvoiceModel{ var id: String = UUID().uuidString var status: String = "Pending" var comment: String = "" var dueDate: Date = Date.now var createdAt: Date = Date.now var updated: Date = Date.now var amount: Double = 0.0 var paymentTerms: String = "Once" var paymentMethod: String = "" var paymentDates: [Date] = [] var numOfPayments: Int = 1 @Relationship(deleteRule: .nullify, inverse: \OrderModel.invoice) var order: OrderModel? @Relationship(deleteRule: .nullify) var customer: CustomerModel? init() {} } This is my modelContainer in my index structure: @main struct Aje: App { var appContainer: ModelContainer = { let schema = Schema([UserModel.self, TaskModel.self, SubtaskModel.self, InventoryModel.self, SupplierModel.self]) let config = ModelConfiguration(schema: schema, isStoredInMemoryOnly: false, allowsSave: true, groupContainer: .automatic, cloudKitDatabase: .automatic) do{ return try ModelContainer(for: schema, configurations: [config]) }catch{ fatalError("An error has occured: \(error)") } }() var body: some Scene { WindowGroup { ContentView() } .modelContainer(appContainer) } } This works fine but the below after adding the problematic models crashes the app unless CloudKit is disabled @main struct Aje: App { var appContainer: ModelContainer = { let schema = Schema([UserModel.self, TaskModel.self, SubtaskModel.self, InventoryModel.self, SupplierModel.self, InvoiceModel.self, OrderModel.self, CustomerModel.self]) let config = ModelConfiguration(schema: schema, isStoredInMemoryOnly: false, allowsSave: true, groupContainer: .automatic, cloudKitDatabase: .automatic) do{ return try ModelContainer(for: schema, configurations: [config]) }catch{ fatalError("An error has occured: \(error)") } }() var body: some Scene { WindowGroup { ContentView() } .modelContainer(appContainer) } }

If an app is using top-level models, meaning they exist outside the VersionedSchema enum, is it safe to keep them outside of the VersionedSchema enum and use a migration plan for simple migrations. Moving the models within the VersionedSchema enum I believe would change the identity of the models and result in data being lost, although correct me if I'm wrong in that statement. The need presently is just to add another variable to the model and then set that variable within the init function: var updateId = UUID() The app is presently in TestFlight although I'd like to preserve data for users that are currently using the app. The data within SwiftData is synchronized with CloudKit and so I'd also like to avoid any impact to synchronization. Any thoughts on this would be greatly appreciated.

Hi there! I'm making an app that stores data for the user's profile in SwiftData. I was originally going to use UserDefaults but I thought SwiftData could save Images natively but this is not true so I really could switch back to UserDefaults and save images as Data but I'd like to try to get this to work first. So essentially I have textfields and I save the values of them through a class allProfileData. Here's the code for that: import SwiftData import SwiftUI @Model class allProfileData { var profileImageData: Data? var email: String var bio: String var username: String var profileImage: Image { if let data = profileImageData, let uiImage = UIImage(data: data) { return Image(uiImage: uiImage) } else { return Image("DefaultProfile") } } init(email:String, profileImageData: Data?, bio: String, username:String) { self.profileImageData = profileImageData self.email = email self.bio = bio self.username = username } } To save this I create a new class (I think, I'm new) and save it through ModelContext import SwiftUI import SwiftData struct CreateAccountView: View { @Query var profiledata: [allProfileData] @Environment(\.modelContext) private var modelContext let newData = allProfileData(email: "", profileImageData: nil, bio: "", username: "") var body: some View { Button("Button") { newData.email = email modelContext.insert(newData) try? modelContext.save() print(newData.email) } } } To fetch the data, I originally thought that @Query would fetch that data but I saw that it fetches it asynchronously so I attempted to manually fetch it, but they both fetched nothing import SwiftData import SwiftUI @Query var profiledata: [allProfileData] @Environment(\.modelContext) private var modelContext let fetchRequest = FetchDescriptor<allProfileData>() let fetchedData = try? modelContext.fetch(fetchRequest) print("Fetched count: \(fetchedData?.count ?? 0)") if let imageData = profiledata.first?.profileImageData, let uiImage = UIImage(data: imageData) { profileImage = Image(uiImage: uiImage) } else { profileImage = Image("DefaultProfile") } No errors. Thanks in advance

I have SwiftData models containing arrays of Codable structs that worked fine before adding CloudKit capability. I believe they are the reason I started seeing errors after enabling CloudKit. Example model: @Model final class ProtocolMedication { var times: [SchedulingTime] = [] // SchedulingTime is Codable // other properties... } After enabling CloudKit, I get this error logged to the console: 'NSKeyedUnarchiveFromData' should not be used to for un-archiving and will be removed in a future release CloudKit Console shows this times data as "plain text" instead of "bplist" format. Other struct/enum properties display correctly (I think) as "bplist" in CloudKit Console. The local SwiftData storage handled these arrays fine - this issue only appeared with CloudKit integration. What's the recommended approach for storing arrays of Codable structs in SwiftData models that sync with CloudKit?

When I used to do Migrations, I always used ETL and then push to a dev system to review/test before going production. The migration support is SwiftData is fine for a little tweak. I might as well just just use new schema and context and write the custom code than use the SwiftData migration support.

Hello, In our app, we’ve modeled our schema using inheritance introduced in iOS 26.0, and we’re implementing SwiftData History to re-fetch models only when necessary. @Model public class Transaction { @Attribute(.preserveValueOnDeletion) public var date: Date = Date() public var amount: Double = 0 public var memo: String? } @Model public final class Spending: Transaction { public var installmentIndex: Int = 1 public var installment: Int = 1 public var installmentID: UUID? } If data has been deleted from database, we need to check a date property to determine whether to re-fetch datas. To do this, we added the preserveValueOnDeletion attribute to date property so we could retrieve it from the History tombstone value. However, after adding this attribute, a crash occurs. There is a console log Could not cast value of type 'Swift.ReferenceWritableKeyPath<Shared.ModelSchemaV5.Transaction, Foundation.Date>' (0x106bf8328) to 'Swift.PartialKeyPath<Shared.ModelSchemaV5.Spending>' (0x1094f21d8). and error log attached StrictMoneyChecking-2025-11-07-105108.txt I also tried this in the recent SampleTrip app, and fetching all history after a deletion causes the same crash. Is this issue currently being worked on or under investigation?

Hi everyone, I'm looking for the correct architectural guidance for my SwiftData implementation. In my Swift project, I have dedicated async functions for adding, editing, and deleting each of my four models. I created these functions specifically to run certain logic whenever these operations occur. Since these functions are asynchronous, I call them from the UI (e.g., from a button press) by wrapping them in a Task. I've gone through three different approaches and am now stuck. Approach 1: @MainActor Functions Initially, my functions were marked with @MainActor and worked on the main ModelContext. This worked perfectly until I added support for App Intents and Widgets, which caused the app to crash with data race errors. Approach 2: Passing ModelContext as a Parameter To solve the crashes, I decided to have each function receive a ModelContext as a parameter. My SwiftUI views passed the main context (which they get from @Environment(\.modelContext)), while the App Intents and Widgets created and passed in their own private context. However, this approach still caused the app to crash sometimes due to data race errors, especially during actions triggered from the main UI. Approach 3: Creating a New Context in Each Function I moved to a third approach where each function creates its own ModelContext to work on. This has successfully stopped all crashes. However, now the UI actions don't always react or update. For example, when an object is added, deleted, or edited, the change isn't reflected in the UI. I suspect this is because the main context (driving the UI) hasn't been updated yet, or because the async function hasn't finished its work. My Question I'm not sure what to do or what the correct logic should be. How should I structure my data operations to support the main UI, Widgets, and App Intents without causing crashes or UI update failures? Here is the relevant code using my third (and current) approach. I've shortened the helper functions for brevity. // MARK: - SwiftData Operations extension DatabaseManager { /// Creates a new assignment and saves it to the database. public func createAssignment( name: String, deadline: Date, notes: AttributedString, forCourseID courseID: UUID, /*...other params...*/ ) async throws -> AssignmentModel { do { let context = ModelContext(container) guard let course = findCourse(byID: courseID, in: context) else { throw DatabaseManagerError.itemNotFound } let newAssignment = AssignmentModel( name: name, deadline: deadline, notes: notes, course: course, /*...other properties...*/ ) context.insert(newAssignment) try context.save() // Schedule notifications and add to calendar _ = try? await scheduleReminder(for: newAssignment) newAssignment.calendarEventIDs = await CalendarManager.shared.addEventToCalendar(for: newAssignment) try context.save() await MainActor.run { WidgetCenter.shared.reloadTimelines(ofKind: "AppWidget") } return newAssignment } catch { throw DatabaseManagerError.saveFailed } } /// Finds a specific course by its ID in a given context. public func findCourse(byID id: UUID, in context: ModelContext) -> CourseModel? { let predicate = #Predicate<CourseModel> { $0.id == id } let fetchDescriptor = FetchDescriptor<CourseModel>(predicate: predicate) return try? context.fetch(fetchDescriptor).first } } // MARK: - Helper Functions (Implementations omitted for brevity) /// Schedules a local user notification for an event. func scheduleReminder(for assignment: AssignmentModel) async throws -> String { // ... Full implementation to create and schedule a UNNotificationRequest return UUID().uuidString } /// Creates a new event in the user's selected calendars. extension CalendarManager { func addEventToCalendar(for assignment: AssignmentModel) async -> [String] { // ... Full implementation to create and save an EKEvent return [UUID().uuidString] } } Thank you for your help.

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?

My app has three main SwiftData models: Collection, SavedItem, and Extract. A Collection can contain subcollections (folders within folders) and SavedItems (files). Each SavedItem can have child Extracts. I'm preparing for the ability for users to be able to share Collections with each other. Currently, my architecture treats each Collection as the root of its own CloudKit zone (a root parent Collection and all of its items and subcollections live in 1 zone). This makes sharing and isolation straightforward, but it also means that moving a SavedItem or subcollection between Collections involves moving it across zones. I’m trying to figure out the best pattern for handling these cross-zone moves while keeping data integrity, relationships, and sharing intact. My understanding is that in CloudKit, and moving a record from Zone A to Zone B would require deleting it from Zone A and recreating it in Zone B - while somehow maintaining the link back to my local SwiftData store. Has anyone run into this or know how best I should handle 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?

Hello, I've a question about performance when trying to render lots of items coming from SwiftData via a @Query on a SwiftUI List. Here's my setup: // Item.swift: @Model final class Item: Identifiable { var timestamp: Date var isOptionA: Bool init() { self.timestamp = Date() self.isOptionA = Bool.random() } } // Menu.swift enum Menu: String, CaseIterable, Hashable, Identifiable { var id: String { rawValue } case optionA case optionB case all var predicate: Predicate<Item> { switch self { case .optionA: return #Predicate { $0.isOptionA } case .optionB: return #Predicate { !$0.isOptionA } case .all: return #Predicate { _ in true } } } } // SlowData.swift @main struct SlowDataApp: App { var sharedModelContainer: ModelContainer = { let schema = Schema([Item.self]) let modelConfiguration = ModelConfiguration(schema: schema, isStoredInMemoryOnly: false) return try! ModelContainer(for: schema, configurations: [modelConfiguration]) }() var body: some Scene { WindowGroup { ContentView() } .modelContainer(sharedModelContainer) } } // ContentView.swift struct ContentView: View { @Environment(\.modelContext) private var modelContext @State var selection: Menu? = .optionA var body: some View { NavigationSplitView { List(Menu.allCases, selection: $selection) { menu in Text(menu.rawValue).tag(menu) } } detail: { DemoListView(selectedMenu: $selection) }.onAppear { // Do this just once // (0..<15_000).forEach { index in // let item = Item() // modelContext.insert(item) // } } } } // DemoListView.swift struct DemoListView: View { @Binding var selectedMenu: Menu? @Query private var items: [Item] init(selectedMenu: Binding<Menu?>) { self._selectedMenu = selectedMenu self._items = Query(filter: selectedMenu.wrappedValue?.predicate, sort: \.timestamp) } var body: some View { // Option 1: touching `items` = slow! List(items) { item in Text(item.timestamp.description) } // Option 2: Not touching `items` = fast! // List { // Text("Not accessing `items` here") // } .navigationTitle(selectedMenu?.rawValue ?? "N/A") } } When I use Option 1 on DemoListView, there's a noticeable delay on the navigation. If I use Option 2, there's none. This happens both on Debug builds and Release builds, just FYI because on Xcode 16 Debug builds seem to be slower than expected: https://indieweb.social/@curtclifton/113273571392595819 I've profiled it and the SwiftData fetches seem blazing fast, the Hang occurs when accessing the items property from the List. Is there anything I'm overlooking or it's just as fast as it can be right now?

I'm experiencing a critical issue with SwiftData custom migrations where objects created during migration appear to be inserted successfully but aren't persisted or found by queries after migration completes. The migration logs show objects being created, but subsequent queries return zero results. I'm migrating from schema version V2 to V2_5, which involves: Renaming Person class to GroupData Keeping the same data structure but changing the class name while keeping the old class. Using a custom migration stage to copy data from old to new schema Below is an extract of my two schema and migration plan: Environment: Xcode 16.0, iOS 18.0, Swift 6.0 SchemaV2 enum LinkMapV2: VersionedSchema { static let versionIdentifier: Schema.Version = .init(2, 0, 0) static var models: [any PersistentModel.Type] { [AnnotationData.self, Person.self, History.self] } @Model final class Person { @Attribute(.unique) var id: UUID var name: String var photo: String var requirement: String var statue: Bool var annotationId: UUID? var number: Int = 0 init(id: UUID = UUID(), name: String = "", photo: String = "", requirement: String = "", status: Bool = false, annotationId: UUID? = nil, number: Int = 0) { self.id = id self.name = name self.photo = photo self.requirement = requirement self.statue = status self.annotationId = annotationId self.number = number } } } Schema V2_5 static let versionIdentifier: Schema.Version = .init(2, 5, 0) static var models: [any PersistentModel.Type] { [AnnotationData.self, Person.self, GroupData.self, History.self] } // Keep the old Person model for migration @Model final class Person { @Attribute(.unique) var id: UUID var name: String var photo: String var requirement: String var statue: Bool var annotationId: UUID? var number: Int = 0 init(id: UUID = UUID(), name: String = "", photo: String = "", requirement: String = "", status: Bool = false, annotationId: UUID? = nil, number: Int = 0) { self.id = id self.name = name self.photo = photo self.requirement = requirement self.statue = status self.annotationId = annotationId self.number = number } } // Add the new GroupData model that mirrors Person @Model final class GroupData { @Attribute(.unique) var id: UUID var name: String var photo: String var requirement: String var status: Bool var annotationId: UUID? var number: Int = 0 init(id: UUID = UUID(), name: String = "", photo: String = "", requirement: String = "", status: Bool = false, annotationId: UUID? = nil, number: Int = 0) { self.id = id self.name = name self.photo = photo self.requirement = requirement self.status = status self.annotationId = annotationId self.number = number } } } Migration Plan static let migrationV2toV2_5 = MigrationStage.custom( fromVersion: LinkMapV2.self, toVersion: LinkMapV2_5.self, willMigrate: { context in do { let persons = try context.fetch(FetchDescriptor<LinkMapV2.Person>()) print("=== MIGRATION STARTED ===") print("Found \(persons.count) Person objects to migrate") guard !persons.isEmpty else { print("No Person data requires migration") return } for person in persons { print("Migrating Person: '\(person.name)' with ID: \(person.id)") let newGroup = LinkMapV2_5.GroupData( id: person.id, // Keep the same ID name: person.name, photo: person.photo, requirement: person.requirement, status: person.statue, annotationId: person.annotationId, number: person.number ) context.insert(newGroup) print("Inserted new GroupData: '\(newGroup.name)'") // Don't delete the old Person yet to avoid issues // context.delete(person) } try context.save() print("=== MIGRATION COMPLETED ===") print("Successfully migrated \(persons.count) Person objects to GroupData") } catch { print("=== MIGRATION ERROR ===") print("Migration failed with error: \(error)") } }, didMigrate: { context in do { // Verify migration in didMigrate phase let groups = try context.fetch(FetchDescriptor<LinkMapV2_5.GroupData>()) let oldPersons = try context.fetch(FetchDescriptor<LinkMapV2_5.Person>()) print("=== MIGRATION VERIFICATION ===") print("New GroupData count: \(groups.count)") print("Remaining Person count: \(oldPersons.count)") // Now delete the old Person objects for person in oldPersons { context.delete(person) } if !oldPersons.isEmpty { try context.save() print("Cleaned up \(oldPersons.count) old Person objects") } // Print all migrated groups for debugging for group in groups { print("Migrated Group: '\(group.name)', Status: \(group.status), Number: \(group.number)") } } catch { print("Migration verification error: \(error)") } } ) And I've attached console output below: Console Output

Description: I'm experiencing a critical issue with SwiftData custom migrations where objects created during migration appear to be inserted successfully but aren't persisted or found by queries after migration completes. The migration logs show objects being created, but subsequent queries return zero results. Problem Details: I'm migrating from schema version V2 to V3, which involves: Renaming Person class to GroupData Keeping the same data structure but changing the class name Using a custom migration stage to copy data from old to new schema Migration Code: swift static let migrationV2toV3 = MigrationStage.custom( fromVersion: LinkMapV2.self, toVersion: LinkMapV3.self, willMigrate: { context in do { let persons = try context.fetch(FetchDescriptor<LinkMapV2.Person>()) print("Found (persons.count) Person objects to migrate") // ✅ Shows 11 objects for person in persons { let newGroup = LinkMapV3.GroupData( id: person.id, // Same UUID name: person.name, // ... other properties ) context.insert(newGroup) print("Inserted GroupData: '\(newGroup.name)'") // ✅ Confirms insertion } try context.save() // ✅ No error thrown print("Successfully migrated \(persons.count) objects") // ✅ Confirms save } catch { print("Migration error: \(error)") } }, didMigrate: { context in do { let groups = try context.fetch(FetchDescriptor<LinkMapV3.GroupData>()) print("Final GroupData count: \(groups.count)") // ❌ Shows 0 objects! } catch { print("Verification error: \(error)") } } ) Console Output: text === MIGRATION STARTED === Found 11 Person objects to migrate Migrating Person: 'Riverside of pipewall' with ID: 7A08C633-4467-4F52-AF0B-579545BA88D0 Inserted new GroupData: 'Riverside of pipewall' ... (all 11 objects processed) ... === MIGRATION COMPLETED === Successfully migrated 11 Person objects to GroupData === MIGRATION VERIFICATION === New GroupData count: 0 // ❌ PROBLEM: No objects found! What I've Tried: Multiple context approaches: Using the provided migration context Creating a new background context with ModelContext(context.container) Using context.performAndWait for thread safety Different save strategies: Calling try context.save() after insertions Letting SwiftData handle saving automatically Multiple save calls at different points Verification methods: Checking in didMigrate closure Checking in app's ContentView after migration completes Using both @Query and manual FetchDescriptor Schema variations: Direct V2→V3 migration Intermediate V2.5 schema with both classes Lightweight migration with @Attribute(originalName:) Current Behavior: Migration runs without errors Objects appear to be inserted successfully context.save() completes without throwing errors But queries in didMigrate and post-migration return empty results The objects seem to exist in a temporary state that doesn't persist Expected Behavior: Objects created during migration should be persisted and queryable Post-migration queries should return the migrated objects Data should be available in the main app after migration completes Environment: Xcode 16.0+ iOS 18.0+ SwiftData Swift 6.0+ Key Questions: Is there a specific way migration contexts should be handled for data to persist? Are there known issues with object persistence in custom migrations? Should we be using a different approach for class renaming migrations? Is there a way to verify that objects are actually being written to the persistent store? The migration appears to work perfectly until the verification step, where all created objects seem to vanish. Any guidance would be greatly appreciated! Additional Context from my investigation: I've noticed these warning messages during migration that might be relevant: text SwiftData.ModelContext: Unbinding from the main queue. This context was instantiated on the main queue but is being used off it. error: Persistent History (76) has to be truncated due to the following entities being removed: (Person) This suggests there might be threading or context lifecycle issues affecting persistence. Let me know if you need any additional information about my setup or migration configuration!