Cocoa® Programming

The NSObject Base Class

The Objective-C language allows the creation of any number of base classes, sometimes called root classes. A base class is a class that does not have a superclass. However, Cocoa depends on the fact that almost all classes have a common base class. In Cocoa, the common-base class is NSObject.

The NSObject class is an abstract class meaning that programs use instances of classes that inherit from NSObject, but rarely use instances of NSObject itself. NSObject is a powerful class and a complete description of all its features is beyond the scope of this chapter. The NSObject class documentation that comes with the Apple developer tools is excellent and complete. Some key features of NSObject that enable much of the power ...