I have an app that is already running with CoreData, and I want to allow the users to upload their data to iCloud so, in the case they need to delete their apps or change devices, they don't lose it. Every time the app is opened, there is a synchronization that happens between CoreData and a JSON file fixture, in order to fill the app with its base values (creating NSManagedObject instances from the aforementioned fixture). Before the iCloud sync, the CoreData model had some constraints for different entities, to enforce uniqueness, but these had to be stripped since CloudKit doesn't support them. Most of these constraints were basically ids that came from the JSON and represent an item in our Firebase database. Given that, I want to make the underlying CKRecord.id the same as these ids, so I can avoid the situation where, if a person open the app in a second device, the fixture data is repeated, since the fixture runs before the sync with the iCloud happens. Is that possible? Any help would be appreciated.