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Hour 7. Declaring a Class in an Interface File > Exploring Class Hierarchies
Exploring Class Hierarchies
Except for NSObject, which is the root class for Cocoa, every class has a superclass. You can follow up the hierarchy until you get to NSObject.
Calling Superclass Methods
The methods of each superclass are available to a child class, but only one at a time. For example, consider the imaginary hierarchy shown here:
NSObject
NSView
draw
MyAbstractView
draw
MYView
draw
MYSpecificView
The draw method is implemented in NSView, MyAbstractView, and MYView. If you instantiate MYView, the draw method in MYView is performed when you send a message to the instance of MYView. If you instantiate an instance of NSView, the NSView draw method is performed when you send a draw message to that instance. In terms of the architecture, each of the classes’ methods are separate.
