Leaving CloudKit
CloudKit is one of the best-kept secrets in the Apple platform stack. For years it has quietly powered sync, storage, and sharing for our apps — for free, with zero servers to run, and with end-to-end encryption we didn’t have to design ourselves. And yet, we’re moving off it.
[…]
When a user’s data won’t sync, we have no view into what happened on Apple’s side. We’ve spent years bolting telemetry onto
NSPersistentCloudKitContainer.eventChangedNotificationjust to find out why a save failed — and even with that, we’re guessing from client-side error codes. There are no server logs we can pull, no admin view into the user’s zone.[…]
CloudKit is supposed to “just work” across Apple platforms. In practice every target has been its own debugging project: macOS only synced on app restart for a while, Apple Watch silently stopped syncing because a user hadn’t accepted a new iCloud ToS — a failure mode we couldn’t even surface to them — and one of our entitlement bugs was reported to us by Apple. AppleTV sync is still flaky in user reports today.
[…]
iCloud signed-out, iCloud full, family-sharing edge cases — CloudKit hands all of this to the client. We’ve built distinct account-state UI for iOS, macOS, watchOS, tvOS, and visionOS, with localizations for each. “Warn the user when their iCloud is full” has been an open ticket of ours since 2025 because we can’t reliably detect it.
Via Fatbobman:
[For] small teams, CloudKit offers an almost unbelievable combination of features[…] But as their product evolved, CloudKit’s limitations became increasingly apparent[…] and most importantly, the inability to truly expand toward the Web and cross-platform ecosystems. Eventually, César’s team migrated to a Supabase/Postgres-based synchronization architecture.
Previously:
- CloudKit Problems With iOS 26.4
- CloudKit Throttles and Debugging
- NSPersistentCloudKitContainer in 2022
- Syncing Core Data With CloudKit and NSPersistentCloudKitContainer
