Do unique constraints work on an NSPersistentCloudKitContainer?

The documentation for Creating a Core Data Model for CloudKit states that

Unique constraints aren’t supported.


but I've tried to set one up and it seems to be working fine (locally, I haven't tried syncing yet) on Xcode 11.5 & iOS 13.5.

If I'm not mistaken, when NSPersistentCloudKitContainer was first introduced Xcode displayed an error if you tried to add a constraint to an Entity, but that doesn't seem to happen anymore. Has this restriction been lifted or do I just remember it incorrectly and it never showed any errors?

If the restriction has not been lifted, does anyone know how to make sure that Entities are not duplicated? It'll be easy to add a cleanup operation after every sync, but so far I am not aware of any way to know when the sync has fully finished.

Thanks.
Do unique constraints work on an NSPersistentCloudKitContainer?
 
 
Q