Returns whether this object or any of the objects it contains has uncommitted changes.
- iOS 5.0+
- macOS 10.8+
- Mac Catalyst 13.0+
- watchOS 2.0+
YES if there are uncommitted changes; otherwise,
Saving and Restoring State
Returns whether this object has ever been saved.
Merges changes to this object with the latest saved values.
Returns this object to its saved state.
Rolls back the property values of this object to its original state when it was first fetched.