Hi, Not sure how to describe my issue best: I am using SwiftData and CloudKit to store my data. In the past, when I tested my app on different devices, the data would sync between the devices automatically. For whatever reason this has stopped now and the data no longer syncs. No matter what I do, it feels as if all the data is actually stored just locally on each device. How can I check if the data is actually stored in the cloud and what could be reasons, why its no longer synching between my devices (and yes, I am logged in with the same Apple ID on all devices). Thanks for any hint! Max

When deleting a SwiftData entity, I sometimes encounter the following error in a document based SwiftUI app: Fatal error: Unexpected backing data for snapshot creation: SwiftData._FullFutureBackingData<MyEntityClass> The deletion happens in a SwiftUI View and the code used to retrieve the entity is standard (the ModelContext is injected from the @Environment): let myEntity = modelContext.model(for: entityIdToDelete) modelContext.delete(myEntity) Unfortunately, I haven't yet managed to isolate this any further in order to come up with a reproducible PoC. Could you give me further information about what this error means?

I have an app with SwiftData and CloudKit sync enabled, it was working fine but I recently noticed that the sync with CloudKit is not working anymore. All the changes are persisted locally just fine. When running in simulator (iOS 26/iPhone 17 Pro) I get the following error in the console: CoreData+CloudKit: -[NSCloudKitMirroringDelegate recoverFromError:](2317): <NSCloudKitMirroringDelegate: 0x600003d14c30> - Attempting recovery from error: Error Domain=NSCocoaErrorDomain Code=134421 "Export encountered an unhandled exception while analyzing history in the store." UserInfo={NSLocalizedFailureReason=Export encountered an unhandled exception while analyzing history in the store., NSUnderlyingException=-[NSEntityDescription objectID]: unrecognized selector sent to instance 0x60000351aec0} I already tried Reseting the environment back to production in CloudKit and Erasing all Contents and Settings in the simulator but I keep getting the same error. Is there something else I can do to fix this?

Hello Apple Developer Forum, I got the following statement from the AI model. It seems it is also reflecting my real-world experience. Where do I find an official source that fully describes the array on swiftData model behaviour? When a SwiftData model contains an array of value types, such as [String] or [Int], the array's order is preserved

I have an app that uses a Share Extension that allows the user to share videos, from Files and Photos etc., the video URL and some related data is then persisted with SwiftData and synchronized with CloudKit. This code has worked consistently for a long time although recently, with iOS 26 and recent builds of iOS 18, I have observed that the video is either not saved to SwiftData (iOS 26.0), or available locally when the app is opened on the same device where the share occurred, but not synchronized to other devices (iOS 18.7 and iOS 26.1 beta). Assuming the video is opened locally after being shared into the app, it is typically synchronized with CloudKit to other devices although it's not as reliable as it should be. Is there a reliable approach in the Share Extension to ensure that the data is saved to the local SwiftData database and then synchronized with CloudKit. I suspect it could be that the lifetime of the Share Extension has become even more constrained in recent OS updates that the process ends before it has the opportunity to save and synchronize the data. Any thoughts on how to ensure this is reliable would be greatly appreciated. The data saved is not too large as it consists only of the video URL and not the data of the video itself.

Hi, I did cloudkit synchronization using swiftdata. However, synchronization does not occur automatically, and synchronization occurs intermittently only when the device is closed and opened. For confirmation, after changing the data in Device 1 (saving), when the data is fetched from Device 2, there is no change. I've heard that there's still an issue with swiftdata sync and Apple is currently troubleshooting it, is the phenomenon I'm experiencing in the current version normal?

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

Hi, I am currently developing a document-based application with additional WindowGroup for macOS and have encountered a challenge related to document container management. Specifically, I need to open a windowGroup that shares the same container as the one used in the DocumentGroup. However, my current approach of using a global shared model container has led to unintended behavior: any new document created is linked to existing ones, and changes made in one document are reflected across all documents. To address this issue, I am looking for a solution that allows each newly created document to be individualized while still sharing the document container with all relevant WindowGroups that require access to the data it holds. I would greatly appreciate any insights or recommendations you might have on how to achieve this. struct Todo: App { var body: some Scene { DocumentGroup(editing: Item.self, contentType: .item) { ContentView() } WindowGroup(for: Item.self) { $item in ItemView(item:$item) .modelContainer(Of DocumentGroup above) } } } Thank you for your time and assistance. Best regards,

I'm experiencing a significant UI freeze in my SwiftUI app that uses SwiftData with CloudKit sync. When users tap a button to present a sheet for the first time after app launch, the entire UI becomes unresponsive for 5-10 seconds. Subsequent sheet presentations work fine. App Architecture Service layer: An @Observable class marked with @MainActor that orchestrates operations Persistence layer: A @ModelActor class that handles SwiftData operations SwiftUI views: Using @Environment to access the service layer The structure looks like this: @Observable @MainActor final class MyServices { let persistence: DataPersistence init(modelContainer: ModelContainer) { self.persistence = DataPersistence(modelContainer: modelContainer) } func addItem(title: String) async { // Creates and saves an item through persistence layer } } @ModelActor actor DataPersistence { func saveItem(_ item: Item) async { // Save to SwiftData } } The app initializes the ModelContainer at the Scene level and passes it through the environment: @main struct MyApp: App { let container = ModelContainer(for: Item.self) var body: some Scene { WindowGroup { ContentView() .modelContainer(container) .environment(MyServices(modelContainer: container)) } } } The Problem When a user taps the "Add Item" button which presents a sheet: Button("Add Item") { showingAddSheet = true } .sheet(isPresented: $showingAddSheet) { AddItemView(onAdd: { title in await services.addItem(title: title) }) } The UI freezes completely for 5-10 seconds on first presentation. During this time: The button remains in pressed state No UI interactions work The app appears completely frozen After the freeze, the sheet opens and everything works normally This only happens on the first sheet presentation after app launch. I suspect it's related to SwiftData's ModelContext initialization happening on the main thread despite using @ModelActor, but I'm not sure why this would happen given that ModelActor should handle background execution. Environment iOS 18 SwiftData with CloudKit sync enabled Xcode 16 Swift 6 Has anyone experienced similar freezes with SwiftData and @ModelActor? Is there something wrong with how I'm structuring the initialization of these components? The documentation suggests @ModelActor should handle background operations automatically, but the freeze suggests otherwise. Any insights would be greatly appreciated!

I'm developing an app that uses CloudKit synchronization with SwiftData and on visionOS I added an App Settings bundle. I have noticed that sometimes, when the app is open and the user changes a setting from the App Settings bundle, the following fatal error occurs: SwiftData/BackingData.swift:831: Fatal error: This model instance was destroyed by calling ModelContext.reset and is no longer usable. The setting is read within the App struct in the visionOS app target using @AppStorage and this value is in turn used to set the passthrough video dimming via the .preferredSurroundingsEffect modifier. The setting allows the user to specify the dimming level as dark, semi dark, or ultra dark. The fatal error appears to occur intermittently although the first time it was observed was after adding the settings bundle. As such, I suspect there is some connection between those code changes and this fatal error even though they do not directly relate to SwiftData.

I have been working on an app for the past few months, and one issue that I have encountered a few times is an error where quick subsequent deletions cause issues with detached tasks that are triggered from some user actions. Inside a Task.detached, I am building an isolated model context, querying for LineItems, then iterating over those items. The crash happens when accessing a Transaction property through a relationship. var byTransactionId: [UUID: [LineItem]] { return Dictionary(grouping: self) { item in item.transaction?.id ?? UUID() } } In this case, the transaction has been deleted, but the relationship existed when the fetch occurred, so the transaction value is non-nil. The crash occurs when accessing the id. This is the error. SwiftData/BackingData.swift:1035: Fatal error: This model instance was invalidated because its backing data could no longer be found the store. PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(backing: SwiftData.PersistentIdentifier.PersistentIdentifierBacking.managedObjectID(0xb43fea2c4bc3b3f5 &lt;x-coredata://A9EFB8E3-CB47-48B2-A7C4-6EEA25D27E2E/Transaction/p1756&gt;))) I see other posts about this error and am exploring some suggestions, but if anyone has any thoughts, they would be appreciated.

How does SwiftData work with background operations? CoreData had background context that could be used to avoid UI hang for heavy operations. Is there an equivalent in SwiftData, and if so, do I have to merge changes or does it save directly to persistent store?

Hi all, As you know, when using SwiftData Cloudkit, all relationships are required to be optional. In my app, which is a list app, I have a model class Project that contains an array of Subproject model objects. A Subproject also contains an array of another type of model class and this chain goes on and on. In this type of pattern, it becomes really taxxing to handle the optionals the correct way, i.e. unwrap them as late as possible and display an error to the user if unable to. It seems like most developers don't even bother, they just wrap the array in a computed property that returns an empty array if nil. I'm just wondering what is the recommended way by Apple to handle these optionals. I'm not really familiar with how the CloudKit backend works, but if you have a simple list app that only saves to the users private iCloud, can I just handwave the optionals like so many do? Is it only big data apps that need to worry? Or should we always strive to handle them the correct way? If that's the case, why does it seem like most people skip over them? Be great if an Apple engineer could weigh in.

Every time I insert a subclass (MYShapeLayer) into the model context, the app crashes with an error: DesignerPlayground crashed due to fatalError in BackingData.swift at line 908. Never access a full future backing data - PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(backing: SwiftData.PersistentIdentifier.PersistentIdentifierBacking.managedObjectID(0xb2dbc55f3f4c57f2 <x-coredata://B1E3206B-40DE-4185-BC65-4540B4705B40/MYShapeLayer/p1>))) with Optional(A6CA4F89-107F-4A66-BC49-DD7DAC689F77) struct ContentView: View { @Environment(\.modelContext) private var modelContext @Query private var designs: [MYDesign] var layers: [MYLayer] { designs.first?.layers ?? [] } var body: some View { NavigationStack { List { ForEach(layers) { layer in Text(layer.description) } } .onAppear { let design = MYDesign(title: "My Design") modelContext.insert(design) try? modelContext.save() } .toolbar { Menu("Add", systemImage: "plus") { Button(action: addTextLayer) { Text("Add Text Layer") } Button(action: addShapeLayer) { Text("Add Shape Layer") } } } } } private func addTextLayer() { if let design = designs.first { let newLayer = MYLayer(order: layers.count, kind: .text) newLayer.design = design modelContext.insert(newLayer) try? modelContext.save() } } private func addShapeLayer() { if let design = designs.first { let newLayer = MYShapeLayer(shapeName: "Ellipse", order: layers.count) newLayer.design = design modelContext.insert(newLayer) try? modelContext.save() } } } #Preview { ContentView() .modelContainer(for: [MYDesign.self, MYLayer.self, MYShapeLayer.self], inMemory: true) } @Model final class MYDesign { var title: String = "" @Relationship(deleteRule: .cascade, inverse: \MYLayer.design) var layers: [MYLayer] = [] init(title: String = "") { self.title = title } } @available(iOS 26.0, macOS 26.0, *) @Model class MYLayer { var design: MYDesign! var order: Int = 0 var title: String = "" init(order: Int = 0, title: String = "New Layer") { self.order = order self.title = title } } @available(iOS 26.0, macOS 26.0, *) @Model class MYShapeLayer: MYLayer { var shapeName: String = "" init(shapeName: String, order: Int = 0) { self.shapeName = shapeName super.init(order: order) } }

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)) } } } }

The 'unique' attribute is a really nice feature, BUT. In some of my apps, the unique identifier for an object is a combination of multiple attributes. (Example: a book title is not unique, but a combination of book title and author list is.) How do I model this with SwiftData? I cannot use @Attribute(.unique) on either the title OR the author list, but I want SwiftData to provide the same "insert or update" logic. Is this possible?

Hello Developer Support, I have the following code and the following crash. How can the swift data model unable to decode and yet able to display the decoded value at the same time?! What's missing here? CODE: @Model final class DisplayCache { init(point: MKMapPoint) { self.point = point } var point: MKMapPoint } CRASH SwiftData/ModelCoders.swift:1069: Fatal error: Unable to decode this value MKMapPoint(x: 74358466.66307731, y: 97927933.41833577)

Hi all, In my SwiftUI / SwiftData / Cloudkit app which is a series of lists, I have a model object called Project which contains an array of model objects called subprojects: final class Project1 { var name: String = "" @Relationship(deleteRule: .cascade, inverse: \Subproject.project) var subprojects : [Subproject]? init(name: String) { self.name = name self.subprojects = [] } } The user will select a project from a list, which will generate a list of subprojects in another list, and if they select a subproject, it will generate a list categories and if the user selects a category it will generate another list of child objects owned by category and on and on. This is the pattern in my app, I'm constantly passing arrays of model objects that are the children of other model objects throughout the program, and I need the user to be able to add and remove things from them. My initial approach was to pass these arrays as bindings so that I'd be able to mutate them. This worked for the most part but there were two problems: it was a lot of custom binding code and when I had to unwrap these bindings using init?(_ base: Binding<Value?>), my program would crash if one of these arrays became nil (it's some weird quirk of that init that I don't understand at al). As I'm still learning the framework, I had not realized that the @model macro had automatically made my model objects observable, so I decided to remove the bindings and simply pass the arrays by reference, and while it seems these references will carry the most up to date version of the array, you cannot mutate them unless you have access to the parent and mutate it like such: project.subcategories?.removeAll { $0 == subcategory } project.subcategories?.append(subcategory) This is weirding me out because you can't unwrap subcategories before you try to mutate the array, it has to be done like above. In my code, I like to unwrap all optionals at the moment that I need the values stored in them and if not, I like to post an error to the user. Isn't that the point of optionals? So I don't understand why it's like this and ultimately am wondering if I'm using the correct design pattern for what I'm trying to accomplish or if I'm missing something? Any input would be much appreciated! Also, I do have a small MRE project if the explanation above wasn't clear enough, but I was unable to paste in here (too long), attach the zip or paste a link to Google Drive. Open to sharing it if anyone can tell me the best way to do so. Thanks!

I'm implementing SwiftData with inheritance in an app. I have an Entity class with a property name. This class is inherited by two other classes: Store and Person. The Entity model has a one-to-many relationship with a Transaction class. I can list all my Entity models in a List with a @Query annotation without a problem. However, then I try to access the name property of an Entity from a Transaction relationship, the app crashes with the following error: Thread 1: Fatal error: Never access a full future backing data - PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(backing: SwiftData.PersistentIdentifier.PersistentIdentifierBacking.managedObjectID(0x96530ce28d41eb63 <x-coredata://DABFF7BB-C412-474E-AD50-A1F30AC6DBE9/Person/p4>))) with Optional(F07E7E23-F8F0-4CC0-B282-270B5EDDC7F3) From my attempts to fix the issue, I noticed that: The crash seems related to the relationships with classes that has inherit from another class, since it only happens there. When I create new data, I can usually access it without any problem. The crash mostly happens after reloading the app. This error has been mentioned on the forum (for example here), but in a context not related with inheritance. You can find the full code here. For reference, my models looks like this: @Model class Transaction { @Attribute(.unique) var id: String var name: String var date: Date var amount: Double var entity: Entity? var store: Store? { entity as? Store } var person: Person? { entity as? Person } init( id: String = UUID().uuidString, name: String, amount: Double, date: Date = .now, entity: Entity? = nil, ) { self.id = id self.name = name self.amount = amount self.date = date self.entity = entity } } @Model class Entity: Identifiable { @Attribute(.preserveValueOnDeletion) var name: String var lastUsedAt: Date @Relationship(deleteRule: .cascade, inverse: \Transaction.entity) var operations: [Transaction] init( name: String, lastUsedAt: Date = .now, operations: [Transaction] = [], ) { self.name = name self.lastUsedAt = lastUsedAt self.operations = operations } } @available(iOS 26, *) @Model class Store: Entity { @Attribute(.unique) var id: String var locations: [Location] init( id: String = UUID().uuidString, name: String, lastUsedAt: Date = .now, locations: [Location] = [], operations: [Transaction] = [] ) { self.locations = locations self.id = id super.init(name: name, lastUsedAt: lastUsedAt, operations: operations) } } In order to reproduce the error: Run the app in the simulator. Click the + button to create a new transaction. Relaunch the app, then click on any transaction. The app crashes when it tries to read te name property while building the details view.

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?