Subclasses to substitute a new class for instances during keyed archiving.
- iOS 2.0+
- macOS 10.2+
- tvOS 9.0+
- watchOS 2.0+
The object will be encoded as if it were a member of the class. This property is overridden by the encoder class and instance name to class encoding tables. If this property is
nil, the result of this property is ignored.