Enables the recording of undo operations.
- iOS 3.0+
- macOS 10.0+
- tvOS 9.0+
- watchOS 2.0+
Because undo registration is enabled by default, it is often used to balance a prior
disable message. Undo registration isn’t actually re-enabled until an enable message balances the last disable message in effect. Raises an
NSInternal if invoked while no
disable message is in effect.