Returns the credential state for the given user in a completion handler.
- iOS 13.0+
- macOS 10.15+
- Mac Catalyst 13.0+
- tvOS 13.0+
- watchOS 6.0+
An opaque string associated with the Apple ID that your app receives in the credential’s
userproperty after performing a successful authentication request.
A block the method calls to report the state and an optional error condition.