The default value of the attribute.
- iOS 3.0+
- macOS 10.4+
- UIKit for Mac 13.0+Beta
- tvOS 9.0+
- watchOS 2.0+
- Core Data
Default values are retained by a managed object model, not copied. This means that attribute values do not have to implement the
NSCopying protocol, however it also means that you should not modify any objects after they have been set as default values.
Setting the default value raises an exception if the receiver’s model has been used by an object graph manager.