Just to clarify, in the newer iOS versions there are two classes of identifier that replace the UUID: identifierForVendor is not shared across vendors, but it

Just to clarify, in the newer iOS versions there are two classes of identifier that replace the UUID: identifierForVendor is not shared across vendors, but it is shared across apps from the same vendor. identiferForAdvertising is shared across all apps, but it is not shared between devices and can be reset at any time by the user. (I think the user can suppress it altogether, but I'm not 100% sure.)