Programming in Objective-C, Fifth Edition

Entering Your Code

Now we’re ready to modify some of your project files. Notice that a class called AppDelegate was created for you. An application delegate subclass is created for every new iOS application you create. In general, in this class are methods that control the application’s execution. This includes such things as what to do when the application starts, when it enters and leaves the background, when the system tells it it’s using too much memory, and when it terminates. We won’t make any changes to this class in either of the two examples in this chapter.

A second class was also created for you called ViewController. As you can see, Xcode creates interface and implementation sections for you in the corresponding .h and .m files. A ...