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How to figure out sync errors in Production?
I'm using SwiftData with CloudKit private database. I was able to identify the error on my device by debugging in Xcode with com.apple.CoreData.SQLDebug flag. However, in Production, I couldn't find a way to get the cause of errors. I tried inspecting the error coming from eventChangedNotification. The NSPersistentCloudKitContainer.Event error does not contain any underlying error (neither CKError.userInfo nor in NSError.underlyingError). It only reports a partial failure with CKErrorDomain code 2. If a user encounter an error, there seems to be no way to retrieve the error details. Is there any way to access the error details or logs in Production?
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Best approach to prevent SwiftData .transformable migration on iOS 26.1
We have an unreleased SwiftData app for iOS18+. While we were testing I saw reports on the forum about unexpected database migrations for codable arrays on iOS26.1. I'd like to ask a couple of questions: 1- Does this issue originate from the new Xcode version, or is it specific to iOS 26.1? 2- Is it possible to change our attribute so that users on older iOS versions receive the same model, preventing a migration from being triggered when they upgrade to iOS 26.1? One of our models looks like this: struct Point: Codable, Hashable { let x: Int let y: Int } @Model class Grid { private(set) var gridId: String = "" var points: [Point] = [] var updatedAt: Date = Date() private(set) var createdAt: Date = Date() #Index<Grid>([\.gridId]) ... } I can think of some options like: // 1 @Attribute(.transformable(by: CustomJsonTransformer.self)) var points: [Point] = [] // 2 @Attribute(.externalStorage) var points: [Point] = [] // 3 var points: Data = Data() // store points as data However, I'm not sure which one to use. What would you recommend to handle this, or is there a better strategy you would suggest?
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Nov ’25
SwiftData & CloudKit: Deduplication Logic
I followed these two resources and setup history tracking in SwiftData. SwiftData History tracking: Track model changes with SwiftData history For data deduplication: Sharing Core Data objects between iCloud users In the sample app (CoreDataCloudKitShare), a uuid: UUID field is used for deduplication logic. It sorts the entities by their uuids, reserves the first one, and marks the others as deduplicated. Would it be a viable solution to use a createdAt: Date field for the sort operation instead of a uuid field, or are dates inherently problematic?
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Jan ’25