Objective-C

Chapter 3. Adding Objects

In This Chapter

• Learning object-oriented terminology

• Working with objects in Objective-C

• Creating classes and class hierarchies

• Defining properties

• Writing class and object methods

• Declaring member variables

Fundamentally speaking, all software development technologies are ultimately aimed at solving one specific problem. The problem is that thinking about more than one idea at a time is difficult for human beings. So, all these technologies enable us to compartmentalize and encapsulate our ideas into reusable packages that can be mixed and matched in novel ways to solve new problems.

You've already seen how procedural programming — breaking our ideas out into procedures that we can reuse — enables exactly this kind of compartmentalization and encapsulation. Procedural programming was a revolutionary concept when it was initially introduced early in computer science history. However, it had one major flaw: Procedures have no mechanism for storing state within themselves. Typically, procedural programmers work around this limitation by either passing state variables into the procedures along with the parameters that are necessary for the procedure to do its work, or by relying on global variables to store their state instead. Both of these are not ideal solutions.

Passing state variables into the procedures can quickly get out of hand because, as your programs become more complex, they require more and more state to be preserved between procedure calls.

Using global ...