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Defining a Class

Much of object-oriented programming consists of writing the code for new objects—defining new classes. In Objective-C, classes are defined in two parts:

• An interface that declares the methods and instance variables of the class and names its superclass

• An implementation that actually defines the class (contains the code that implements its methods)

These are typically split between two files, sometimes however a class definition may span several files through the use of a feature called a “category.” Categories can compartmentalize a class definition or extend an existing one. Categories are described in “Categories and Extensions.”

Contents:

Source Files
Class Interface
Class Implementation

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