Stefan Pauwels (@stefanpauwels.mastodon.social.ap.brid.gy)

Multiplatform CoreData or SwiftData with CloudKit – Checklist If you want to use CoreData or SwiftData with CloudKit and build for iOS and Mac (and probably other Apple platforms) here are the things you might have to consider (i.e. things I learned the hard way): ## CloudKit Environment Xcode Debug Build & Run uses the Development Environment on CloudKit. Testflight and App Store Releases use the Production Environment. There are ways to use production environment for debug builds, but not the other way around. ## Keep Environments separate But if you both test and use your app on the same machine (hello indie Mac developer), all these use the same local ~/Library/Containers folder. This will create a big mess with your data, syncing the same local data with different CloudKit environments. To prevent this mess I configure seperate Bundle IDs for Release and Debug builds (e.g. “ch.zoziapps.leviathan” and “ch.zoziapps.leviathan.debug”). This creates distinct folders in ~/Libray/Containers and makes it easier to separate test and productive use of your app. Make sure to do this for all of your apps targets. ## App Extensions/Embedded Targets and App Groups Speaking of all targets: If you have an extension that needs to access the same data, you have to place your container in an AppGroup. I would create two separate AppGroups (again, a release and a debug version) and initialize the container with the correct app group: static func createModelContainer() -> ModelContainer { let schema = Schema([ Item.self, ]) #if DEBUG let groupName = "group.loremipsum.debug" #else let groupName = "group.loremipsum" #endif let modelConfiguration = ModelConfiguration( schema: schema, isStoredInMemoryOnly: false, groupContainer: .identifier(groupName), cloudKitDatabase: .automatic) do { return try ModelContainer(for: schema, configurations: [modelConfiguration]) } catch { fatalError("Could not create ModelContainer: \(error)") } } Both app groups need to be checked in the Capabilities section. ## Configure CloudKit Framework Also make sure that CloudKit appears under “Frameworks, Libraries and Embedded Content” (options “Always Used” and “Do not embed”) otherwise CloudKit won’t sync, at least on the Mac (I think). ## Deploy Schema Don’t forget to deploy the schema (and later changes) to production in the iCloud Console. https://stefan.pauwels.ch/2025/06/17/multiplatform-coredata-or-swiftdata-with-cloudkit-checklist/