Is there is Identifier for iCloud ID regardless how many times user change email address ? i want as developer use user iCloud ID as an account ID . however sometimes users may cheat on this and change iCloud email address so i want know if there is a unique ID for each iCloud account
Just store a value (such as an UUID) under a known key in the iCloud account of the user. You can then check for the existence (and value) of that key in subsequent runs of your application.