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CloudKit Documentation

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How often iCloud will sync with local swiftData?
Hi, I have developed a calendar app with swiftData. I have set it to sync iCloud. When testing it, it seems that everything is fine. But after it's released, today, I uninstalled it and reinstalled it again. And I found that iCloud hasn't sync with local swiftData for six days. I have lost six days agenda and relevant information. I have checked the document, and it's said that there is no method to force to sync with iCloud. How to solve the issue? I think that the users can't forgive that it hasn't synced for six days. Best Wishes,
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358
Mar ’25
can't reach CloudKit dashboard
Hello there, I have a problem reaching the CloudKit dashboard. Every time I login, the login successes but then I get the error: An error has caused this web page to stop working correctly. This also happens when I click on the Button CloudKit dashboard. Then I can reload the page, but the same errors occurs again and again. Can someone help me with this problem? Thank you very much
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165
May ’25
Using SwiftData with a local and CloudKit backed configuration at the same time
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?
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373
Oct ’25
Core Data slow to save
iOS 18.2, Swift, Xcode 16.2 I have a Core Data model with two entities - WarehouseArea (of which there is only one object) and StockReeipt (of which there are a couple of hundred thousand). Each StockReceipt must be linked to a WarehouseArea, and a WarehouseArea can be linked to zero, one or many StockReceipts. My problem is that when I create and add one more StockReceipt, the Core Data save takes over 3 seconds to complete. I don't understand why this is so slow. Saving the initial 200,000 StockReceipts only takes 5-6 seconds. When I enable SQL logging I can see that when the WarehouseArea attribute is being set on a StockReceipt, Core Data fetches all of the other StockReceipts (I don't know why) but that only takes 0.2 seconds and none of those StockReceipts are modified, so there shouldn't be any need to process them when saving the context. I have prepared a test project which can be found at https://github.com/DaleReilly/CoreDataSaveTester . Running the project will produce NSLog output showing the times before and after the slow save. Please help me understand what is going on in the background and tell me if there is any way I can speed this up?
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764
Jan ’25
CloudKit and SwiftData not syncing on MacOS
I have a simple app that uses SwiftUI and SwiftData to maintain a database. The app runs on multiple iPhones and iPads and correctly synchronises across those platforms. So I am correct setting Background Modes and Remote Notifications. I have also correctly setup my Model Configuration and ModelContainer (Otherwise I would expect syncing to fail completely). The problem arises when I run on a Mac (M1 or M3) either using Mac Designed for iPad or Mac Catalyst. This can be debugging in Xcode or running the built app. Then the app does not reflect changes made in the iPhone or iPad apps unless I follow a specific sequence. Leave the app, (e.g click on a Finder window), then come back to the app (i.e click on the app again). Now the app will show the changes made on the iPhone/iPad. It looks like the app on the Mac is not processing remote notifications when in the background - it only performs them when the app has just become active. It also looks like the Mac is not performing these sync operations when the app is active. I have tried waiting 30 minutes and still the sync doesn't happen unless I leave the app and come back to it. I am using the same development CloudKit container in all cases
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751
Sep ’25
SwiftData + CKSyncEngine
Hi, I'm building a habit tracking app for iOS and macOS. I want to use up to date technologies, so I'm using SwiftUI and SwiftData. I want to store user data locally on device and also sync data between device and iCloud server so that the user could use the app conveniently on multiple devices (iPhone, iPad, Mac). I already tried SwiftData + NSPersistentCloudKitContainer, but I need to control when to sync data, which I can't control with NSPersistentCloudKitContainer. For example, I want to upload data to server right after data is saved locally and download data from server on every app open, on pull-to-refresh etc. I also need to monitor sync progress, so I can update the UI and run code based on the progress. For example, when downloading data from server to device is in progress, show "Loading..." UI, and when downloading finishes, I want to run some app business logic code and update UI. So I'm considering switching from NSPersistentCloudKitContainer to CKSyncEngine, because it seems that with CKSyncEngine I can control when to upload and download data and also monitor the progress. My database schema (image below) has relationships - "1 to many" and "many to many" - so it's convenient to use SwiftData (and underlying CoreData). Development environment: Xcode 16.1, macOS 15.1.1 Run-time configuration: iOS 18.1.1, macOS 15.1.1 My questions: 1-Is it possible to use SwiftData for local data storage and CKSyncEngine to sync this local data storage with iCloud? 2-If yes, is there any example code to implement this? I've been studying the "CloudKit Samples: CKSyncEngine" demo app (https://github.com/apple/sample-cloudkit-sync-engine), but it uses a very primitive approach to local data storage by saving data to a JSON file on disk. It would be very helpful to have the same demo app with SwiftData implementation! 3-Also, to make sure I don't run into problems later - is it okay to fire data upload (sendChanges) and download (fetchChanges) manually with CKSyncEngine and do it often? Are there any limits how often these functions can be called to not get "blocked" by the server? 4-If it's not possible to use SwiftData for local data storage and CKSyncEngine to sync this local data storage with iCloud, then what to use for local storage instead of SwiftData to sync it with iCloud using CKSyncEngine? Maybe use SwiftData with the new DataStore protocol instead of the underlying CoreData? All information highly appreciated! Thanks, Martin
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1.4k
Dec ’24
Avoid Duplicate Records with CloudKit & CoreData
When my app starts it loads data (of vehicle models, manufacturers, ...) from JSON files into CoreData.  This content is static. Some CoreData entities have fields that can be set by the user, for example an isFavorite boolean field. How do I tell CloudKit that my CoreData objects are 'static' and must not be duplicated on other devices (that will also load it from JSON files). In other words, how can I make sure that the CloudKit knows that the record created from JSON for vehicle model XYZ on one device is the same record that was created from JSON on any other device? I'm using NSPersistentCloudKitContainer.
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3.3k
Jun ’25
SwiftData - Cloudkit stopped syncing
I have an app that from day 1 has used Swiftdata and successfully sync'd across devices with Cloudkit. I have added models to the data in the past and deployed the schema and it continued to sync across devices. Sometime I think in June.2025 I added a new model and built out the UI to display and manage it. I pushed a version to Test Flight (twice over a matter of 2 versions and a couple of weeks) and created objects in the new model in Test Flight versions of the app which should push the info to Cloudkit to update the schema. When I go to deploy the schema though there are no changes. I confirmed in the app that Cloudkit is selected and it's point to the correct container. And when I look in Cloudkit the new model isn't listed as an indes. I've pushed deploy schema changes anyway (more than once) and now the app isn't sync-ing across devices at all (even the pre-existing models aren't sync-ing across devices). I even submitted the first updated version to the app store and it was approved and released. I created objects in the new model in production which I know doesn't create the indexes in the development environment. But this new model functions literally everywhere except Cloudkit and I don't know what else to do to trigger an update.
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1
215
Sep ’25
caches directory counts towards app storage?
throughout all of Foundation's URL documentation, its called out in multiple places that data stored inside an app sandox's caches directory doesn't count towards data and documents usage in the settings app but in practice, it looks like storing data there does in fact count towards documents & data for the app i'm trying to understand if the docs are wrong, if theres a bug in the settings app, or if this is a mistake on my part
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822
Dec ’24
CoreData/CloudKit 0xdead10cc
I’m getting a 0xdead10cc crash in a basic CoreData/CloudKit application. I only have one CoreData save call and its made when the app is in the foreground and it's minor so I don't think its being caused by that. My best guess is that it's related to background syncing of CloudKit. Does anyone know how to fix it? I've been advised that adding the following code around any saves will fix it, but it seems weird that this is the solution. I would expect the inner CoreData/CloudKit engine to handle this. ProcessInfo().performActivity(reason: "Persisting to context") { // Save to context here } Here is the crashing thread Thread 7: 0 libsystem_kernel.dylib 0x00000001edc086f4 guarded_pwrite_np + 8 (:-1) 1 libsqlite3.dylib 0x00000001ca71b6e4 seekAndWrite + 456 (sqlite3.c:44287) 2 libsqlite3.dylib 0x00000001ca6d5df4 unixWrite + 180 (sqlite3.c:44365) 3 libsqlite3.dylib 0x00000001ca723b90 pagerWalFrames + 872 (sqlite3.c:67093) 4 libsqlite3.dylib 0x00000001ca6d5b14 sqlite3PagerCommitPhaseOne + 316 (sqlite3.c:70409) 5 libsqlite3.dylib 0x00000001ca6c6494 sqlite3BtreeCommitPhaseOne + 172 (sqlite3.c:81106) 6 libsqlite3.dylib 0x00000001ca6c605c vdbeCommit + 1136 (sqlite3.c:94124) 7 libsqlite3.dylib 0x00000001ca69f778 sqlite3VdbeHalt + 1340 (sqlite3.c:94534) 8 libsqlite3.dylib 0x00000001ca6c0618 sqlite3VdbeExec + 42648 (sqlite3.c:103922) 9 libsqlite3.dylib 0x00000001ca6b56c0 sqlite3_step + 960 (sqlite3.c:97886) 10 CoreData 0x00000001a459ab38 _execute + 128 (NSSQLiteConnection.m:4614) 11 CoreData 0x00000001a45fe004 -[NSSQLiteConnection commitTransaction] + 728 (NSSQLiteConnection.m:3278) 12 CoreData 0x00000001a469888c _executeGenerateObjectIDRequest + 388 (NSSQLCore_Functions.m:6021) 13 CoreData 0x00000001a46986a4 -[NSSQLGenerateObjectIDRequestContext executeRequestCore:] + 28 (NSSQLObjectIDRequestContext.m:42) 14 CoreData 0x00000001a45fb380 -[NSSQLStoreRequestContext executeRequestUsingConnection:] + 240 (NSSQLStoreRequestContext.m:183) 15 CoreData 0x00000001a45fb0a8 __52-[NSSQLDefaultConnectionManager handleStoreRequest:]_block_invoke + 60 (NSSQLConnectionManager.m:307) 16 CoreData 0x00000001a45fafe0 __37-[NSSQLiteConnection performAndWait:]_block_invoke + 48 (NSSQLiteConnection.m:755) 17 libdispatch.dylib 0x00000001a4357fa8 _dispatch_client_callout + 20 (object.m:576) 18 libdispatch.dylib 0x00000001a43677fc _dispatch_lane_barrier_sync_invoke_and_complete + 56 (queue.c:1104) 19 CoreData 0x00000001a45b5ba4 -[NSSQLiteConnection performAndWait:] + 176 (NSSQLiteConnection.m:752) 20 CoreData 0x00000001a45b5a68 -[NSSQLDefaultConnectionManager handleStoreRequest:] + 248 (NSSQLConnectionManager.m:302) 21 CoreData 0x00000001a45b5938 -[NSSQLCoreDispatchManager routeStoreRequest:] + 228 (NSSQLCoreDispatchManager.m:60) 22 CoreData 0x00000001a45b573c -[NSSQLCore dispatchRequest:withRetries:] + 172 (NSSQLCore.m:4044) 23 CoreData 0x00000001a46737b4 -[NSSQLCore _obtainPermanentIDsForObjects:withNotification:error:] + 1324 (NSSQLCore.m:2830) 24 CoreData 0x00000001a460ba98 -[NSSQLCore _prepareForExecuteRequest:withContext:error:] + 272 (NSSQLCore.m:2946) 25 CoreData 0x00000001a460a0f8 __65-[NSPersistentStoreCoordinator executeRequest:withContext:error:]_block_invoke.547 + 8988 (NSPersistentStoreCoordinator.m:2995) 26 CoreData 0x00000001a45d6660 -[NSPersistentStoreCoordinator _routeHeavyweightBlock:] + 264 (NSPersistentStoreCoordinator.m:668) 27 CoreData 0x00000001a45ded28 -[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 1200 (NSPersistentStoreCoordinator.m:2810) 28 CoreData 0x00000001a4655988 -[NSManagedObjectContext save:] + 984 (NSManagedObjectContext.m:1593) 29 CoreData 0x00000001a46f47dc __52+[NSCKEvent beginEventForRequest:withMonitor:error:]_block_invoke_2 + 352 (NSCKEvent.m:76) 30 CoreData 0x00000001a45c28f0 developerSubmittedBlockToNSManagedObjectContextPerform + 476 (NSManagedObjectContext.m:3984) 31 libdispatch.dylib 0x00000001a4357fa8 _dispatch_client_callout + 20 (object.m:576) 32 libdispatch.dylib 0x00000001a43677fc _dispatch_lane_barrier_sync_invoke_and_complete + 56 (queue.c:1104) 33 CoreData 0x00000001a4615c34 -[NSManagedObjectContext performBlockAndWait:] + 308 (NSManagedObjectContext.m:4108) 34 CoreData 0x00000001a46f45ac __52+[NSCKEvent beginEventForRequest:withMonitor:error:]_block_invoke + 192 (NSCKEvent.m:66) 35 CoreData 0x00000001a4825e68 -[PFCloudKitStoreMonitor performBlock:] + 92 (PFCloudKitStoreMonitor.m:148) 36 CoreData 0x00000001a46f4394 +[NSCKEvent beginEventForRequest:withMonitor:error:] + 256 (NSCKEvent.m:61) 37 CoreData 0x00000001a47cc6ec __57-[NSCloudKitMirroringDelegate _performExportWithRequest:]_block_invoke + 260 (NSCloudKitMirroringDelegate.m:1433) 38 CoreData 0x00000001a47c9970 __92-[NSCloudKitMirroringDelegate _openTransactionWithLabel:assertionLabel:andExecuteWorkBlock:]_block_invoke + 72 (NSCloudKitMirroringDelegate.m:957) 39 libdispatch.dylib 0x00000001a4356248 _dispatch_call_block_and_release + 32 (init.c:1549) 40 libdispatch.dylib 0x00000001a4357fa8 _dispatch_client_callout + 20 (object.m:576) 41 libdispatch.dylib 0x00000001a435f5cc _dispatch_lane_serial_drain + 768 (queue.c:3934) 42 libdispatch.dylib 0x00000001a4360158 _dispatch_lane_invoke + 432 (queue.c:4025) 43 libdispatch.dylib 0x00000001a436b38c _dispatch_root_queue_drain_deferred_wlh + 288 (queue.c:7193) 44 libdispatch.dylib 0x00000001a436abd8 _dispatch_workloop_worker_thread + 540 (queue.c:6787) 45 libsystem_pthread.dylib 0x0000000227213680 _pthread_wqthread + 288 (pthread.c:2696) 46 libsystem_pthread.dylib 0x0000000227211474 start_wqthread + 8 (:-1)
3
0
798
Jan ’25
Can personal information be taken from creatorUserRecordID in a CKrecord?
I am using cloudkit to save users high scores in a public database. The preference over using Game Center is because of simplicity and works really well for what I want to achieve. I simply want to let users know their global position. Because of data privacy laws the app asks the user for their permission to submit their score each time they get a new high score. However, I have noticed that CKRecords under 'created' and 'modified' in addition to UTC time and date also contain creatorUserRecordID. Could this be a privacy issue? Can you extract any personal information from this? Can this be used to track back to the user? Is it linked to CKUserIdentity which I understand does contain personal information, although as I understand you need users consent to get this information. Under creatorUserRecordID it says... "Every user of the app has a unique user record that is empty by default. Apps can add data to the user record on behalf of the user, but don’t store sensitive data in it" Currently I simply ask the user if they are happy to submit their score. But do I need to point out that it also stores a creatorUserRecordID? Obviously I don't want to do this if it is not needed as the user will 1) Probably not understand what a creatorUserRecordID is and 2) It makes the question complicated and will likely make most people refuse to submit their score. If it is a privacy issue, is there anyway to stop a CKRecord creating this ID and simply save a score? All I need is a list of scores so the app can determine their current position. If creatorUserRecordID does not contain any personal details and cannot be tracked back to the user please let me know, so I can be reassured that my current set up is fine and I am not causing any privacy issues! This post did seem to indicate you may possibly be able to fetch personal details?? https://stackoverflow.com/questions/55782166/how-do-i-fetch-any-info-about-user-that-modified-ckrecord
3
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314
Mar ’25
UIImage causes memory to run out
I have a project that currently has data saved locally and I'm trying to get it to sync over multiple devices. Currently basic data is syncing perfectly fine, but I'm having issues getting the images to convert to data. From what I've researched it because I'm using a UIImage to convert and this caches the image It works fine when there's only a few images, but if there's several its a pain The associated code func updateLocalImages() { autoreleasepool { let fetchRequest: NSFetchRequest&lt;Project&gt; = Project.fetchRequest() fetchRequest.predicate = NSPredicate(format: "converted = %d", false) fetchRequest.sortDescriptors = [NSSortDescriptor(keyPath: \Project.statusOrder?.sortOrder, ascending: true), NSSortDescriptor(keyPath: \Project.name, ascending: true)] do { let projects = try viewContext.fetch(fetchRequest) for project in projects { currentPicNumber = 0 currentProjectName = project.name ?? "Error loading project" if let pictures = project.pictures { projectPicNumber = pictures.count for pic in pictures { currentPicNumber = currentPicNumber + 1 let picture : Picture = pic as! Picture if let imgData = convertImage(picture: picture) { picture.pictureData = imgData } } project.converted = true saveContext() } } } catch { print("Fetch Failed") } } } func convertImage(picture : Picture)-&gt; Data? { let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask) let path = paths[0] if let picName = picture.pictureName { let imagePath = path.appendingPathComponent(picName) if let uiImage = UIImage(contentsOfFile: imagePath.path) { if let imageData = uiImage.jpegData(compressionQuality: 0.5) { return imageData } } } return nil }```
3
0
1k
Jan ’25
CloudKit keyvalue pair debug ?
Hello ! I am using this iCloud key value pair mechanism to save small app configuration between iOS and tvOS. I would say it is working. But when I go back and forth between debug and release (TestFlight) modes, it is like both apps are not connected anymore. I spend a lot of time restarting all devices, rebuilding, activating / deactivating iCloud capabilities in the Xcode project. It is like the app is mixing debug and release data. Is there an easy way to check what is happening exactly ? I know there's nothing on CloudKit console, so .... Thank you Frederic
3
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346
Mar ’25
joblinkapp's registerview mistake
I am working on a SwiftUI project using Core Data. I have an entity called AppleUser in my data model, with the following attributes: id (UUID), name (String), email (String), password (String), and createdAt (Date). All attributes are non-optional. I created the corresponding Core Data class files (AppleUser+CoreDataClass.swift and AppleUser+CoreDataProperties.swift) using Xcode’s automatic generation. I also have a PersistenceController that initializes the NSPersistentContainer with the model name JobLinkModel. When I try to save a new AppleUser object using: let user = AppleUser(context: viewContext) user.id = UUID() user.name = "User1" user.email = "..." user.password = "password1" user.createdAt = Date()【The email is correctly formatted, but it has been replaced with “…” for privacy reasons】 try? viewContext.save() I get the following error in the console:Core Data save failed: Foundation._GenericObjCError.nilError, [:] User snapshot: ["id": ..., "name": "User1", "email": "...", "password": "...", "createdAt": ...] All fields have valid values, and the Core Data model seems correct. I have also tried: • Checking that the model name in NSPersistentContainer(name:) matches the .xcdatamodeld file (JobLinkModel) • Ensuring the AppleUser entity Class, Module, and Codegen are correctly set (Class Definition, Current Product Module) • Deleting duplicate or old AppleUser class files • Cleaning Xcode build folder and deleting the app from the simulator • Using @Environment(.managedObjectContext) for the context Despite all this, I still get _GenericObjCError.nilError when saving a new AppleUser object. I want to understand: 1. Why is Core Data failing to save even though all fields are non-nil and correctly assigned? 2. Could this be caused by some residual old class files, or is there something else in the setup that I am missing? 3. What steps should I take to ensure that Core Data properly recognizes the AppleUser entity and allows saving? Any help or guidance would be greatly appreciated.
3
0
130
Sep ’25
SwiftData: filtering against an array of PersistentIdentifiers
I would like to have a SwiftData predicate that filters against an array of PersistentIdentifiers. A trivial use case could filtering Posts by one or more Categories. This sounds like something that must be trivial to do. When doing the following, however: let categoryIds: [PersistentIdentifier] = categoryFilter.map { $0.id } let pred = #Predicate<Post> { if let catId = $0.category?.persistentModelID { return categoryIds.contains(catId) } else { return false } } The code compiles, but produces the following runtime exception (XCode 26 beta, iOS 26 simulator): 'NSInvalidArgumentException', reason: 'unimplemented SQL generation for predicate : (TERNARY(item != nil, item, nil) IN {}) (bad LHS)' Strangely, the same code works if the array to filter against is an array of a primitive type, e.g. String or Int. What is going wrong here and what could be a possible workaround?
3
0
117
Jun ’25
Friend Connection ( User A / User B) Problem
I implemented the cloudkit function, where users can connect with each other. The problem is, that if User A is doing a friend request and User B is accepting the request. The friend entry is correct visible for User B but not for User A. I can see in cloud kit that after the accepted request, the friend connection is set up correctly, also with the correct userID, but it not showing up for User A (the one that send the request)
3
0
404
Mar ’25
iOS 17.2 Update, Confusing SwiftData Update !
Hi, Before the iOS 17.2 update the saving behavior of SwiftData was very straightforward, by default it saves to persistence storage and can be configured to save in memory only. Now it saves to memory by default and to make it save to persistence storage we need to use modelContext.Save(). But if we don't quit the App the changes will be saved after a while to persistence storage even without running modelContext.Save() ! How confusing can that be for both developer and the user ! Am I missing something here ? -- Kind Regards
3
0
425
Mar ’25