Not an answer I’m afraid, but perhaps a related problem. They’ve definitely changed something deep at the OS level which is even affecting the CloudKit syncing of apps built with the iOS 14 SDK many months ago (ie. my app!) if run on an iOS 15 device, let alone apps built with the iOS 15 SDK!
This failure of syncing started to occur when iOS 15 beta 4 was released - prior to this it was all working normally, as it did in iOS 13 & iOS 14. From beta 4 the entire structure of the console log outputs for NSPersistentCloudKitContainer
changed, so something fundamental changed with CloudKit at this time.
In my case, it seems it has trouble syncing Core Data relationships and NSPersistentCloudKitMirrorringDelegate
gets stuck in a loop causing CPU & RAM consumption to rise uncontrollably, with the OS killing the app shortly afterwards. No syncing occurs. My Core Data structure has not changed since iOS 14 and my app synced (and still does) just fine on iOS 14 devices.
Other than a reply from a ‘Frameworks Engineer’ briefly, I’ve had no communication from Apple, nor an acknowledgement that this is even an issue, including in my Feedback report - nobody from Apple has replied there. It’s extremely disheartening particularly as they’ve released the Release Candidate and it’s still broken. I’m going to have many very upset users (medical professionals) in a few days.
If it didn’t affect Apps built 6 months ago with the iOS 14 SDK I wouldn’t really be that concerned as I could just hold off my iOS 15 release until this is fixed, but it’s breaking existing apps which is totally unacceptable.
Here’s my thread on it:
https://developer.apple.com/forums/thread/687877
I’ve submitted a Technical Support Incident (at my expense) now that iOS 15 is ‘final’ in the hope that someone will acknowledge this!