My app uses Core Data to store an synchronise the data. It runs on iOS, iPadOS and now WatchOS. The records are stored in the private and shared CloudKit database. Running the app in developer mode, syncing is fine for all devices. But as soon as I switch to production mode using TestFlight, the Watch only syncs the data of the shared records, while iPad and iPhone still are syncing all records (private and shared) correctly. I run out of ideas where to search for the reason of this problem. I use one module to setup the persistent store for iOS, iPadOs and WatchOS. Any ideas are well come.

It's 2024, and it still seems like the only sure way to cleanly restart cloud sync on an app using NSPersistentCloudKitContainer is to uninstall and reinstall the app. No need to describe how bad that solution is... Am I missing something? Is there a better way to safely trigger such a restart of the sync (even if it means losing unsaved data and overwriting with what's in the cloud - which is what a reinstall does anyway)?

SwiftData includes support for CloudKit sync. However, I don't see any way to add conflict resolution behavior. For example, if different devices set different values for a field, or if a relationship is orphaned because of a deletion on another device, the application has to handle this somehow. In Core Data (which SwiftData wraps), you can handle this with the conflict resolution system (docs) and classes like NSMergePolicy. Is any of this accessible in SwiftData? If not, how do you deal with conflicts when syncing a SwiftData model with the cloud?

Recently, I have made quite extensive changes to my schema and need to migrate my CoreData + CloudKit model to a new version. The changes require me to use a custom NSEntityMigrationPolicy because I have a rather complex mapping between some old entities and new entities. I have added a new model version. Deleted some entities, and added some entities. I have defined the NSEntityMigrationPolicy with createDestinationInstances(forSource:in:manager:) and createRelationships(forDestination:in:manager:). I have created a new Core Data Mapping Model. This was probably unnecessary. Within the Core Data Mapping Model, I have specified Custom Policy for all entities. In my container setup, I added two options, as below: storeDescription.setOption(false as NSNumber, forKey: NSMigratePersistentStoresAutomaticallyOption) storeDescription.setOption(false as NSNumber, forKey: NSInferMappingModelAutomaticallyOption) I mostly followed a "Core Data Heavyweight Migration" guide. I'm unable to share the link, but it can be quite easily found on the web. (It's not for CloudKit specifically.) When I run my app, I am getting the most basic of errors, which is: The managed object model version used to open the persistent store is incompatible with the one that was used to create the persistent store. So I guess that migration wasn't even attempted, which makes sense because I set NSMigratePersistentStoresAutomaticallyOption to false. I tried to go beyond what I could find on the web and attempted to manually initialize migration: let sourceModel = container.persistentStoreCoordinator.managedObjectModel guard let modelURL = Bundle.main.url(forResource: "MyModelName", withExtension: "xcdatamodeld") else { fatalError("Unable to locate model file.") } guard let destinationModel = NSManagedObjectModel(contentsOf: modelURL) else { fatalError("Unable to load destination model.") } let migrationManager = NSMigrationManager(sourceModel: sourceModel, destinationModel: destinationModel) let mappingModel = NSMappingModel(from: [Bundle.main], forSourceModel: sourceModel, destinationModel: destinationModel)! migrationManager.currentEntityMapping.entityMigrationPolicyClassName = "MyMigrationPolicyClassName" I am then stuck at the migrateStore(from:type:mapping:to:type:) method. It seems to target only local storage, not CloudKit. Otherwise, what do I provide for URLs and types? Any guidance for custom logic CoreData with CloudKit migration would be greatly appreciated.

I have been working on an ios application which I decided to use the new SwiftData architecture, and I now have realized that SwiftData does not support public or shared databases using SwiftData. I am a new and upcoming Swift developer, who has been self learning the Apple Swift technology. I just learned in this forum that Swift Data does not support Public and Shared Data and I also understand that no plans that have been announced to addressed this feature in the IOS 18 release time frame. The use case for my application is to implement a social type application, something like applications including X, facebook, etc. These type of applications appear to use Public, Shared and Private data in various existing Apple application. I would like to complete an application using Swift using ICloud, but I must assume that these current social applications are using other technologies. I am assuming you can do this in Core Data, but my understanding is Apple is asking that we use Swift Data to replace core data. I also am assuming that Swift data is built on core data technology layers. So ... to me it seems hopeful, somehow, to accomplish this using IOS 17 and follow the recommend Swift Data Path. What are my options for completing these data objectives in IOS? I hope I am addressing these questions in the proper and best forum? Much thanks for any suggestions.

Hi, We are having problems with IOs Quick Look not working. Specifically, the AR button being greyed out after having opened the Scene / AR model previously. This is all running off our Web-App. What we have figured out is clearing the device's cache solves the issue and the greyed out button turns blue and clickable again. We are receiving this issue very inconsistently though - on iPad as well as iPhone and on both newer and older IOs versions. Very happy for any responses and advice to solve this issue as its behaviour makes the quick look function - even if it's great (when it works) unviable for Production (because it doesn't work consistently). Best Regards

How can we identify whether the remote change notification is triggered because some data was changed on a different device and it is downloaded from CloudKit, or it is triggered from the current device because new entity was saved into database. Because this notification is posted when both remote data is downloaded or local data is created. It would be great if there is a way to understand the origin of the notification.

I am using a Mac Catalyst app and saving the content of the app in core data. After uninstalling the app the saved core data file is not getting deleted. Due to this I am having major bugs during launch of the app. My requirement is core data contents should be removed once the app is uninstalled. Anybody with solutions for this?

Has anyone successfully persisted Color, particularly in SwiftData? So far my attempts have failed: Making Color conform to Codable results in a run time error (from memory something about ColorBox). Color.Resolved already conforms Codable but this results in "SwiftData/ModelCoders.swift:124: Fatal error: Composite Coder only supports Keyed Container" None of the other color types conform to Codable (CGColor, NSColor and UIColor) so does the swift language really not have a persistable color type?

CoreData: Zone metadata is missing it's encoded share data but is marked for a mutation: <CKRecordZoneID: 0x600003f044e0; zoneName=com.apple.coredata.cloudkit.share.30BE5FAE-3FE0-4142-90C4-E78FFA90B2A2, ownerName=defaultOwner> - <decode: bad range for [%@] got [offs:312 len:1242 within:0]>

Hello, I have class file, which should save data coreData and Im only able to save data via ui. Do you have any example, how can I save data in core data via class files? Greeting Fabian

Hi, I have been working on some kind of network filtering app for iOS using Content Filter Provider. And I have stored rules for each domain. As of right now, I use UserDefaults with my app's bundle suite to store and observe rules. I have also read this documentation page for UserDefaults link. Is it okay to use UserDefaults in my case, if I have rules added/modified dynamically as the flow is intercepted, or should I pick some other approach like Core Data, SwiftData, etc.? Thank you!

I am currently writing an app that is about writing stories. As of now, it is fairly simple: ContentView is your "Collection" of stories. PopupView is when you click on a button in ContentView. In popup view you enter the story title. Once you do that, you are brought to a blank page which is StoryView, where the NavigationTitle is what your story title is. Once I finish the story and leave the page / StoryView, it is still there, but once I close the app on my phone and reopen it, the story is gone and is not saved. I am a relatively new developer, so ive been relying on ChatGPT and Google Gemini for the saving parts of this, but it rarely works, and the furthest ive gotten with it is that it saves the story title but doesn't save the content of the story. I have a feeling that the AI is overdoing it as well. If anyone could help, please do so. Ive been trying to fix this for days. If you need me to provide any code, I am happy to do so. [Edited by Moderator]

Hello. I recently released a new version (2.6) of my CloudKit syncing CoreData based app. The new version uses v18 of my data model. V18 is exactly like v17, except for a new optional string field in one of the entities. I diffed the two model versions to be extra sure. During my test I did not encounter any crash, and I also tested automatic migration, installing 2.55 and building 2.6 on top of it. No troubles. However my crash logger reports a number of crashes among my users. It's not a huge numbers (10 users over about 900 or more) but I am surprised it crashes at all. The crash happens when I call NSPersistentCloudKitContainer.loadPersistentStores, I get this error in the completion block: The model used to open the store is incompatible with the one used to create the store" I always assumed these slight changes (new field added to an existing model) did not require a manual migration. Any suggestions?

I am trying to profile my app for 'Data Persistence', but I am not getting any data in the Instruments. I tried restarting Xcode and Mac, still no progress. It is showing blank graph for faults, fetches and saves

We currently have a shoebox-based architecture but want to transition to a document-based architecture, so UIManagedDocument seems like an obvious choice. However, the UIManagedDocument API seems outdated given the relatively newer NSPersistentContainer API. Also, it’s not clear if UIManagedDocument’s managedObjectContext can be used on the main thread or not. Ideally, I would like to see a persistentContainer property added to UIManagedDocument which could then be used to obtain the view context or a background managed object context. Does anyone have any suggestions on the latest best practices for document-based architectures using CoreData? I’m more interested in Swift implementations, but knowing best practices for SwiftUI and SwiftData would be helpful too.

persist images even after the app is uninstalled, if we reinstall the app can we display same images in app? but our app not use any cloud or server. Thanks in advance.

I am building an app that manages ScreenTime and I would like to persist the tokens of which apps are frequently limited to CoreData locally. I attempted to do so by converting to a string but was unable to find a way to initialize an ActivityCategoryToken with a string. Is this possible? Am I going about it the wrong way? Thanks.

What sets the SwiftData framework apart from traditional iOS data storage solutions like Core Data or Realm? Could you elaborate on SwiftData's unique features and architecture that enable developers to efficiently manage data in their Swift projects? How does SwiftData enhance the development experience by seamlessly integrating with Swift's language features and paradigms

I recently discovered the new documentation for enabling CloudKit sync with SwiftData. A key step I was missing in my previous setup was this step: Initialize the CloudKit development schema. When I run this though, I get Core Data errors in my log... CoreData: Unsupported attribute type I've noticed that it seems to be preventing adding fields for my model properties that are Codable structs. I've been able to add Codable structs to my SwiftData models synced with CloudKit before. But using Core Data to initialize the CloudKit schema like the documentation suggests just doesn't work. Is there some other way around this? I'm about to just give up on CloudKit sync altogether. I need this to work because I'm trying to add some new fields and populate the fields with data based on existing data during the migration, but this seems to be preventing migration completely. If I don't initialize the schema, I get different errors and the ModelContainer won't initialize at all.