NSObjectProtocol
The group of methods that are fundamental to all Objective-C objects.
Declaration
protocol NSObjectProtocolOverview
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.
The Cocoa root class NSObject adopts this protocol, so all objects inheriting from NSObject have the features described by this protocol.