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?

So i created an App and for some time it was working fine. The app has features to show pdf to users without logging in. I needed to upload all data to cloudkit on public database. I was not having knowledge that there are 2 mode being a noob in coding so after i saved all records in development mode in cloudkit when i published my app, i was not able to see them (Reason because live mode works in Production mode). So i need help now to transfer data from development mode to production mode or any app or code that can help me upload all data in production mode.

Hi everyone In the last 24 hours, I’ve been running into some issues with the CloudKit console. Most of the time, I‘ll get an error stating an error has caused this web page to stop working correctly. Reloading doesn’t fix the issue, nor does using different browsers: Today I’ve got another error, something along the lines of the Console not being able to fetch the teams I’m assigned to and an XHF error pop-up. Has anyone encountered the same issues? After trying multiple times, I’m able to reach my database but it’s a bit frustrating as it’s very unreliable this way. Thanks for your feedback! Dave

Hi everyone, I’m working on an offline-first iOS app using Core Data. I have a question about safe future updates: in my project, I want to be able to add new optional fields to existing Entities or even completely new Entities in future versions — but nothing else (no renaming, deleting, or type changes). Here’s how my current PersistenceController looks: import CoreData struct PersistenceController { static let shared = PersistenceController() let container: NSPersistentContainer init(inMemory: Bool = false) { container = NSPersistentContainer(name: "MyApp") if inMemory { container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null") } container.loadPersistentStores(completionHandler: { (storeDescription, error) in if let error = error as NSError? { print("Core Data failed to load store: \(error), \(error.userInfo)") } }) container.viewContext.automaticallyMergesChangesFromParent = true } } Do I need to explicitly set these properties to ensure lightweight migration works? shouldMigrateStoreAutomatically = true shouldInferMappingModelAutomatically = true Or, according to the documentation, are they already true by default, so I can safely add optional fields and new Entities in future versions without breaking users’ existing data? Thanks in advance for your guidance!

I have a ModelActor that creates a hierarchy of models and returns a PersistentIdentifier for the root. I'd like to do that in a transaction, but I don't know of a good method of getting that identifier if the models are created in a transaction. For instance, an overly simple example: func createItem(timestamp: Date) throws -> PersistentIdentifier { try modelContext.transaction { let item = Item(timestamp: timestamp) modelContext.insert(item) } // how to return item.persistentModelID? } I can't return the item.persistentModelID from the transaction closure and even if I could, it will be a temporary ID until after the transaction is executed. I can't create the Item outside the transaction and just have the transaction do an insert because swift will raise a data race error if you then try to return item.persistentModelID. Is there any way to do this besides a modelContext.fetch* with separate unique identifiers?

I am developing an Xcode app with a job feed, with profile view, with chat eg. I fetch using federatet queries to my microservices thru Apollo Router. Infront of the Apollo Router i Have a Kong that adds a X user ID, that the microservices use for personalized feed and other user info. The info is stored with SwiftData. My thought is that i should add a better way of controlling when i need to fetch. I have a “lastupdateAPI” with different entities (profile, profile picture eg). So when nothing has changed we do not fetch. But rather then using a own API for this, isnt ETag better? Or is it any other recommendations with Xcode Swiftui. Good strategies for not fetching what i already have?

I have an app which uses key-value storage and will not sync data past a certain size -- meaning that device "A" will send the data to the cloud but device "B" will never receive the updated data. Device "B" will receive the NSUbiquitousKeyValueStoreDidChangeExternallyNotification that the KVS changed but the data is empty. The data in in the KVS is comprised of 4 keys, each containing a value of NSData generated by NSKeyedArchiver. The NSData is comprised of property-list data types (e.g. numbers, strings, dates, etc.) I've verified that the KVS meets the limits of: A total of 1 MB per app, with a per-key limit of 1 MB A per-key value size limit of 1 MB, and a maximum of 1024 keys A maximum length for key strings is 64 bytes using UTF8 encoding Also, the app has never received an NSUbiquitousKeyValueStoreQuotaViolationChange notification. Of the 4 keys, 3 of them contain no more than 30 KB of data each. However, one of the keys can contain as much as 160 KB of data which will not sync to another device. Strangely, if I constrain the data to 100 KB it will work, however, that is not ideal as it is a fraction of the necessary data. I don't see any errors in the debug log either. Any suggestions on what to try next to get this working?

I want to get to a point where I can use a small view with a query for my SwiftData model like this: @Query private var currentTrainingCycle: [TrainingCycle] init(/*currentDate: Date*/) { _currentTrainingCycle = Query(filter: #Predicate<TrainingCycle> { $0.numberOfDays > 0 // $0.startDate < currentDate && currentDate < $0.endDate }, sort: \.startDate) } The commented code is where I want to go. In this instance, it'd be created as a lazy var in a viewModel to have it stable (and not constantly re-creating the view). Since it was not working, I thought I could check the same view with a query that does not require any dynamic input. In this case, the numberOfDays never changes after instantiation. But still, each time the app tries to create this view, the app becomes unresponsive, the CPU usage goes at 196%, memory goes way high and the device heats up quickly. Am I holding it wrong? How can I have a dynamic predicate on a View in SwiftUI with SwiftData?

I am following Apple's instruction to sync SwiftData with CloudKit. While initiating the ModelContainer, right after removing the store from Core Data, the error occurs: FAULT: NSInternalInconsistencyException: This NSPersistentStoreCoordinator has no persistent stores (unknown). It cannot perform a save operation.; (user info absent) I've tried removing default.store and its related files/folders before creating the ModelContainer with FileManager but it does not resolve the issue. Isn't it supposed to create a new store when the ModelContainer is initialized? I don't understand why this error occurs. Error disappears when I comment out the #if DEBUG block. Code: import CoreData import SwiftData import SwiftUI struct InitView: View { @Binding var modelContainer: ModelContainer? @Binding var isReady: Bool @State private var loadingDots = "" @State private var timer: Timer? var body: some View { VStack(spacing: 16) { Text("Loading\(loadingDots)") .font(.title2) .foregroundColor(.gray) } .padding() .onAppear { startAnimation() registerTransformers() let config = ModelConfiguration() let newContainer: ModelContainer do { #if DEBUG // Use an autorelease pool to make sure Swift deallocates the persistent // container before setting up the SwiftData stack. try autoreleasepool { let desc = NSPersistentStoreDescription(url: config.url) let opts = NSPersistentCloudKitContainerOptions(containerIdentifier: "iCloud.my-container-identifier") desc.cloudKitContainerOptions = opts // Load the store synchronously so it completes before initializing the // CloudKit schema. desc.shouldAddStoreAsynchronously = false if let mom = NSManagedObjectModel.makeManagedObjectModel(for: [Page.self]) { let container = NSPersistentCloudKitContainer(name: "Pages", managedObjectModel: mom) container.persistentStoreDescriptions = [desc] container.loadPersistentStores { _, err in if let err { fatalError(err.localizedDescription) } } // Initialize the CloudKit schema after the store finishes loading. try container.initializeCloudKitSchema() // Remove and unload the store from the persistent container. if let store = container.persistentStoreCoordinator.persistentStores.first { try container.persistentStoreCoordinator.remove(store) } } // let fileManager = FileManager.default // let sqliteURL = config.url // let urls: [URL] = [ // sqliteURL, // sqliteURL.deletingLastPathComponent().appendingPathComponent("default.store-shm"), // sqliteURL.deletingLastPathComponent().appendingPathComponent("default.store-wal"), // sqliteURL.deletingLastPathComponent().appendingPathComponent(".default_SUPPORT"), // sqliteURL.deletingLastPathComponent().appendingPathComponent("default_ckAssets") // ] // for url in urls { // try? fileManager.removeItem(at: url) // } } #endif newContainer = try ModelContainer(for: Page.self, configurations: config) // ERROR!!! } catch { fatalError(error.localizedDescription) } modelContainer = newContainer isReady = true } .onDisappear { stopAnimation() } } private func startAnimation() { timer = Timer.scheduledTimer( withTimeInterval: 0.5, repeats: true ) { _ in updateLoadingDots() } } private func stopAnimation() { timer?.invalidate() timer = nil } private func updateLoadingDots() { if loadingDots.count > 2 { loadingDots = "" } else { loadingDots += "." } } } import CoreData import SwiftData import SwiftUI @main struct MyApp: App { @State private var modelContainer: ModelContainer? @State private var isReady: Bool = false var body: some Scene { WindowGroup { if isReady, let modelContainer = modelContainer { ContentView() .modelContainer(modelContainer) } else { InitView(modelContainer: $modelContainer, isReady: $isReady) } } } }

It takes a few seconds, sometimes a few minutes for records to be downloaded back from CloudKit when the user reinstalls the app, which leads users to thinking their data was lost. I would like to know if there’s any way to provide a visual feedback about the current CloudKit sync status so I can let users know their data is being in fact downloaded back to their devices.

When a user first downloads my application they are prompted to sign into their apple account via a pop up. I have not had this pop up previously, I believe the change occurred after iOS18. I have functions that do a few things: Retrieves userRecordID Retrieves a userprofile(via userrecordid) from cloudkit.

I have a SwiftData flashcard app which I am syncing with CloudKit using NSPersistentCloudKitContainer. While syncing itself is working perfectly, I have noticed a dramatic increase in the app size after enabling sync. Specifically, without CloudKit, 15k flashcards results in the default.store file being about 4.5 MB. With CloudKit, default.store is about 67 MB. I have inspected the store and found that most of this increase is due to the ANSCKRECORDMETADATA table. My question is, does implementing CloudKit normally cause this magnitude of increase in storage? If it doesn’t, is there something in my model, schema, implementation, etc. that could be causing it? Below are two other posts describing a similar issue, but neither with a solution. I replied to the first one about a month ago. I then submitted this to Developer Technical Support, but was asked to post my question in the forums, so here it is. Strange behavior with 100k+ records in NSPersistentCloudKitContainer Huge increase in sqlite file size after adopting CloudKit

I am using SwiftData with CloudKit to synchronize data across multiple devices, and I have encountered an issue: occasionally, abnormal sync behavior occurs between two devices (it does not happen 100% of the time—only some users have reported this problem). It seems as if synchronization between the two devices completely stops; no matter what operations are performed on one end, the other end shows no response. After investigating, I suspect the issue might be caused by both devices simultaneously modifying the same field, which could lead to CloudKit's logic being unable to handle such conflicts and causing the sync to stall. Are there any methods to avoid or resolve this situation? Of course, I’m not entirely sure if this is the root cause. Has anyone encountered a similar issue?

我正在使用 Core Data 开发一个 SwiftUI 项目。我的数据模型中有一个名为 AppleUser 的实体，具有以下属性：id （UUID）、name （String）、email （String）、password （String） 和 createdAt （Date）。所有属性都是非可选的。 我使用 Xcode 的自动生成创建了相应的 Core Data 类文件（AppleUser+CoreDataClass.swift 和 AppleUser+CoreDataProperties.swift）。我还有一个 PersistenceController，它使用模型名称 JobLinkModel 初始化 NSPersistentContainer。 当我尝试使用以下方法保存新的 AppleUser 对象时： 让用户 = AppleUser（上下文：viewContext） user.id = UUID（） user.name = “用户 1” user.email = “...” user.password = “密码 1” user.createdAt = Date（）【电子邮件格式正确，但已替换为“...”出于隐私原因】 尝试？viewContext.save（） 我在控制台中收到以下错误：核心数据保存失败：Foundation._GenericObjCError.nilError， [：] 用户快照： [“id”： ...， “name”： “User1”， “email”： “...”， “password”： “...”， “createdAt”： ...] 所有字段都有有效值，核心数据模型似乎正确。我还尝试过： • 检查 NSPersistentContainer（name：） 中的模型名称是否与 .xcdatamodeld 文件 （JobLinkModel） 匹配 • 确保正确设置 AppleUser 实体类、模块和 Codegen（类定义、当前产品模块） • 删除重复或旧的 AppleUser 类文件 • 清理 Xcode 构建文件夹并从模拟器中删除应用程序 • 对上下文使用 @Environment（.managedObjectContext） 尽管如此，在保存新的 AppleUser 对象时，我仍然会收到 _GenericObjCError.nilError。 我想了解： 为什么即使所有字段都不是零且正确分配，核心数据也无法保存？ 这可能是由于一些残留的旧类文件引起的，还是我缺少设置中的其他内容？ 我应该采取哪些步骤来确保 Core Data 正确识别 AppleUser 实体并允许保存？ 任何帮助或指导将不胜感激。

I'm trying to handle the serverRecordChanged return code you get in CKError when you have a conflict and your using the savePolicy of ifServerRecordUnchanged. According to the CKError.Code.serverRecordChanged documentation, I should be receiving all three records that I need to do a 3-way merge. The problem is that the ancestorRecord (CKRecordChangedErrorAncestorRecordKey can also be used to look it up in the userInfo) doesn't actually contain a record. It only contains the record metadata. Is there something I need to be doing to get the full ancestorRecord in the CKError? If not is it possible to query iCloud for the ancestorRecord? Given that iCloud has the change history (as I understand it), then it is theoretically possible. I just don't know how to do it if it is possible. Are 3-way merges even possible? The design of the serverRecordChanged looks like that is the intent, but I can't see how to do it with the data that CloudKit is providing.

Hi, I am creating (or trying to) my first app using SwiftData - and I have questions :-) The main question I can't get my head wrapped around is the following: Let's say I have the sample below... @Model class Person { @Relationship(inverse:\Hat.owner) var hat:Hat } @Model class Hat { var owner:Person? } It looks like I am creating a strong reference cycle between the person and the hat objects? And in fact I am seeing these kinds of reference cycles when I look at the memory debugger. Many code samples I have seen so far use this type of relationship declaration... And I am wondering: Am I missing something? Admittedly I don't find many discussions about memory leaks caused by SwiftData despite the syntax being used in many examples? So what is the situation? Did Apple just miss to explain that the inverse: declaration causes memory leaks or is there some kind of magic that I should understand?

We are trying to solve for the following condition with SwiftData + CloudKit: Lots of data in CloudKit Perform "app-reset" to clear data & App settings and start fresh. Reset data models with try modelContext.delete(model:_) myModel.count() confirms local deletion (0 records); but iCloud Console shows expectedly slow process to delete. Old CloudKit data is returning during the On Boarding process. Questions: • Would making a new iCloud Zone for each reset work around this, as the new zone would be empty? We're having trouble finding details about how to do this with SwiftData. • Would CKSyncEngine have a benefit over the default SwiftData methods? Open to hearing if anyone has experienced a similar challenge and how you worked around it!

I'm using Swift Data for an app that requires iOS 18. All of my models conform to a protocol that guarantees they have a 'serverID' String variable. I wrote a function that would allow me to pass in a serverID String and have it fetch the model object that matched. Because I am lazy and don't like writing the same functions over and over, I used a Self reference so that all of my conforming models get this static function. Imagine my model is called "WhatsNew". Here's some code defining the protocol and the fetching function. protocol RemotelyFetchable: PersistentModel { var serverID: String { get } } extension WhatsNew: RemotelyFetchable {} extension RemotelyFetchable { static func fetchOne(withServerID identifier: String, inContext modelContext: ModelContext) -> Self? { var fetchDescriptor = FetchDescriptor<Self>() fetchDescriptor.predicate = #Predicate<Self> { $0.serverID == identifier } do { let allModels = try modelContext.fetch(fetchDescriptor) return allModels.first } catch { return nil } } } Worked great! Or so I thought... I built this and happily ran a debug build in the Simulator and on devices for months while developing the initial version but when I went to go do a release build for TestFlight, that build reliably crashed on every device with a message like this: SwiftData/DataUtilities.swift:65: Fatal error: Couldn't find \WhatsNew. on WhatsNew with fields [SwiftData.Schema.PropertyMetadata(name: "serverID", keypath: \WhatsNew., defaultValue: nil, metadata: Optional(Attribute - name: , options: [unique], valueType: Any, defaultValue: nil, hashModifier: nil)), SwiftData.Schema.PropertyMetadata(name: "title", keypath: \WhatsNew., defaultValue: nil, metadata: nil), SwiftData.Schema.PropertyMetadata(name: "bulletPoints", keypath: \WhatsNew.)>, defaultValue: nil, metadata: nil), SwiftData.Schema.PropertyMetadata(name: "dateDescription", keypath: \WhatsNew., defaultValue: nil, metadata: nil), SwiftData.Schema.PropertyMetadata(name: "readAt", keypath: \WhatsNew.)>, defaultValue: nil, metadata: nil)] It seems (cannot confirm) that something in the release build optimization process is stripping out some metadata / something about these models that makes this predicate crash. Tested on iOS 18.0 and 18.1 beta. How can I resolve this? I have two dozen types that conform to this protocol. I could manually specialize this function for every type myself but... ugh.

If I set my build settings "default actor isolation" to MainActor, how do my @ModelActor actors and model classes need to look like ? For now, I am creating instances of my @ModelActor actors and passing my modelContext container and processing all data there. Everything stays in this context. No models are transferred back to MainActor. Now, after changing my project settings, I am getting a huge amount of warnings. Do I need to set all my model classes to non-isolated and the @ModelActor actor as well? Is there any new sample code to cover this topic ... did not find anything for now. Thanks in advance, Marc

Hello Apple Team, We’re building a CloudKit-enabled Core Data app and would like clarification on the behavior and performance characteristics of Binary Data attributes with “Allows External Storage” enabled when used with NSPersistentCloudKitContainer. Initially, we tried storing image files manually on disk and only saving the metadata (file URLs, dimensions, etc.) in Core Data. While this approach reduced the size of the Core Data store, it introduced instability after app updates and broke sync between devices. We would prefer to use the official Apple-recommended method and have Core Data manage image storage and CloudKit syncing natively. Specifically, we’d appreciate guidance on the following: When a Binary Data attribute is marked as “Allows External Storage”, large image files are stored as separate files on device rather than inline in the SQLite store. How effective is this mechanism in keeping the Core Data store size small on device? Are there any recommended size thresholds or known limits for how many externally stored blobs can safely be managed this way? How are these externally stored files handled during CloudKit sync? Does each externally stored Binary Data attribute get mirrored to CloudKit as a CKAsset? Does external storage reduce the sync payload size or network usage, or is the full binary data still uploaded/downloaded as part of the CKAsset? Are there any bandwidth implications for users syncing via their private CloudKit database, versus developer costs in the public CloudKit database? Is there any difference in CloudKit or Core Data behavior when a Binary Data attribute is managed this way versus manually storing image URLs and handling the file separately on disk? Our goal is to store user-generated images efficiently and safely sync them via CloudKit, without incurring excessive local database bloat or CloudKit network overhead. Any detailed guidance or internal performance considerations would be greatly appreciated. Thank you, Paul Barry Founder & Lead Developer — Boat Buddy / Vessel Buddy iOS App Archipelago Environmental Solutions Inc.