Decodes and returns an object that was previously encoded with any of the
- iOS 2.0+
- macOS 10.0+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
NSCoder’s implementation invokes
decode to decode the object data.
Subclasses may need to override this method if they override any of the corresponding
encode…Object methods. For example, if an object was encoded conditionally using the
encode method, this method needs to check whether the object had actually been encoded.