In an object-oriented programming language such as Objective-C, classes are the building blocks of applications. They are the syntactic construct used to define objects, which are composed of methods and variables. For programmers new to the language, it is important to understand that object-oriented programming (OOP) features are the keystone of all techniques used in Objective-C.
Without a proper understanding of object-oriented design concepts, it is difficult to become proficient in the libraries used on Mac OS X or iOS, since they make heavy use of OOP. For this reason, I start this chapter with a concise overview of OOP. One of my first objectives is to explain how OOP differs from other popular programming paradigms. ...