Apple's documentation seems to say that CloudKit is available on iOS 8.0 and later. But when I test my app using CloudKit on iOS 8.1 and iOS 8.2 simulator, the CloudKit functions don't work. The ubiquityIdentityToken property of an NSFileManager is nil. But the CloudKit functions do work on iOS 8.3 simulator. And, when I had not updated the iCloud account to iCloud Drive, the CloudKit functions also don't work. They only work after I updated the iCloud account to iCloud Drive.
So, does CloudKit on iOS is only available to iOS 8.3 and later and for iCloud accounts that have been updated to iCloud Drive?