Cocoa and Objective-C: Up and Running

Chapter 2. Thinking in Code: Basic C

As a Cocoa programmer, your job is to get your ideas onto the screen. When you write an essay, you use sentences and paragraphs. Writing software works the same way, though you write lines of code instead. Each line performs a task, such as opening a file or displaying an image. When you put enough of these lines of code together, you eventually have an application.

You write these instructions using a programming language. Most Mac and iPhone apps are written in Objective-C, so that’s what you’ll use in this book. The process of converting your ideas into code is called, literally, writing code, and the result is source code. For example, to make your application play the alert sound, you write this line of code:

NSBeep();

There’s one important detail, though. Objective-C is based on a simpler language, called C. In fact, Objective-C isn’t just based on C; it’s all of C plus some other stuff. Programmers like to say it’s a strict superset of C.

So before you start writing Cocoa apps, it helps to learn some C. I’m not going to lead you into the outer limits of the language; you’ll see just enough to get started. If you already know C, you can safely skim this chapter.

Tip

If this seems confusing, just remember that Objective-C is the language that defines how you format your code—the grammar. Cocoa defines what you can make your code do—the overall vocabulary. You create a Cocoa app by writing code in the Objective-C language.

How Code Works

Mac OS X ...