The group of methods that are fundamental to all Objective-C objects.
- iOS 2.0+
- macOS 10.0+
- tvOS 9.0+
- watchOS 2.0+
An object that conforms to this protocol can be considered a first-class object. Such an object can be asked about its:
Class, and the place of its class in the inheritance hierarchy.
Conformance to protocols.
Ability to respond to a particular message.