NSObject protocol groups methods that are fundamental to all Objective-C objects.
- iOS 2.0+
- macOS 10.0+
- tvOS 9.0+
- watchOS 2.0+
If an object conforms to this protocol, it 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
The Cocoa root class,
NSObject, adopts this protocol, so all objects inheriting from
NSObject have the features described by this protocol.