Just a final update. Since 15.5 the NSPersistentCloudKitContainer syncing has been fast, and complete... and seems to now properly sync in the background without causing crashes. Finally... just before iO16 is announced! 🤣

Still no official word from Apple but all my testing with iOS 15.2 (beta 2) is showing it to be working as expected. Hopefully 15.2 will be released soon and this will be marked as resolved.

The official word from Apple is that it's still marked as 'unresolved' but it's quite possible that it has been addressed in the second beta of 15.2 but they're not yet 100% sure it's ready for release. Still... promising developments I think. 🤞🏻

Definitely seems to be resolved with this beta so the official 15.2 should hopefully fix the issue for all our users.

Thanks for posting @danmedia93 - Hopefully we'll see some resolution before the end of the year. I'm really keen to restart work on my update but don't want to touch a thing until this is fixed... it's breaking my existing app as it is!

Wow, that wasn't a swear word! Not sure why it was asterisked out! 😏

Oh, geez... that's not good. The moment I noticed this bug back in iOS15 beta 4 I thought it was a critical bug, but took a while to convince anyone. Still no further updates from Apple at my end but will post as soon as I have any updates. Thanks for submitting a parallel feedback report. Because this bug seems to appear only with complex Core Data structures, a lot of Developers are probably just not seeing it yet.

Tried with iOS 15.2 (beta 1) using a build with Version 13.2 beta (13C5066c) of Xcode. Same issue. Having said that, I was told to wait until I hear back from Apple so while it might not be fixed yet, it might come in a later beta build.

Not yet. The ball is in Apple's court but they know it's an issue and they're working on it. Due to the complexity of finding the bug, fixing it, testing it and merging it with the existing update roadmap, it might take several weeks before it's fixed... but I do know that the Frameworks Engineers are working hard to sort this out. As soon as I here something official in the TSI and I can report it here, I'll let you know.

Thanks for the reply. As I wasn't getting feedback on my feedback I wasn't filled with confidence that uploading anything else would help - it felt like a one-way process. I see the same issue trying to restore the de-identified backup file I sent to FB9412346 (stripped of image data) - there is no way I can simulate this easily as we're talking about syncing thousands of small patient ID label images. A DTS Engineer (who I've liaised with before) has been in touch and I've sent a detailed set of test files & simple instructions to import them to see that, above a certain threshold, it fails to sync. Hopefully he'll see the issue at his end. At least we can now have a back & forth, rather than posting on a forum which is a clunky way to try and resolve this. Because I was led to believe this was a bug (and others have seen it too), and it only started happening at a specific iOS change I've always assumed it wasn't my fault... but maybe it is, and that's why I filed a TSI, but until now was always bounced back to Feedback. In some ways I hope it is me just being a muppet.

I've had an Apple Engineer reply to me now directly with my TSI so hopefully we can get to the bottom of this. When I ingest a small external data file it imports and syncs to iCloud, but as the file size increases (and the relationship counts increases), the delay in syncing and RAM consumption increases significantly to the point where it fails to sync at all. My backup restore is effective a 'large' data file with 19,000 metadata objects - entities, relationships, etc). There is something about relationships that is grinding things to a halt, a problem which didn't exist in iOS 13 & 14.

Nope... that wasn't it - same issue. Saving to the main context made no difference. It's as though NSPersistentCloudKitContainer no longer likes a massive change to the context... weird. I'll try more regular context saves (which slows everything down) to see if that makes a difference. Sigh.

The reason I want a one-on-one in my TSI is that I want to make sure that it's not something I'm doing wrong in my code, when ingesting the backup file, which is only now appearing as a 'bug' due to changes made in iOS 15 beta 4. It's entirely possible that it's my problem, but I don't understand how/why now it's not working (see below).

It's the same (de-identified) backup file I've sent previously (to my Feedback FB9412346). The biggest frustration is that there is no conversation going on in that Feedback thread of mine - I feel like I'm yelling into the void - so I have to keep coming back here for any interaction with Apple - thank you at least for replying here! I just need someone at Apple to download my app, restore that backup file, and observe what (doesn't) happen(s). Even in my TSI I've only received vague replies such as 'it will be fixed in beta 2' but I'm not able to engage with anyone directly to get to the bottom of this quickly. My issue is that this 'backup restore' and subsequent sync to iCloud worked just fine in iOS 15 beta 3 and before (iOS 13 & iOS 14) so something changed... and my app didn't (at least none of that code). It's the same version that's been syncing for a year on iOS 14, etc. If my app no longer syncs, it's going to be the end of it unfortunately. 😔

Still broken in 15.1 beta 2...