I do not see in the sync API how to set the save policy. Does it effectively always use .ifServerRecordUnchanged? If so, does this mean that the app needs to persist the CKRecord that it last provided to or received from the sync engine so that the next time it has changes to submit they will be associated with the proper change tag? Or does the sync engine handle this behind the scenes and the app only needs to worry about the CKRecord.ID? I would like to ensure that if there is a conflict the sync engine has enough information to give me the .ancestorRecord, as I need that for proper resolution.