kABUIDProperty
For example, with the release of iCloud I received emails from some ProfitTrain users who were getting warnings that the link between clients and the AddressBook cards were breaking. Turns out when enabling iCloud your AddressBook records get all new uniqueId values. This isn’t even limited to the initial setup. Turn iCloud contact syncing off and on and it’ll do it again.
Even though the documentation says it’s “guaranteed never to change.”
[…] (kABUIDProperty) property, a string that I think was the same across devices. (Unfortunately, contrary to the documentation, iCloud syncing could cause this permanent identifier to […]