We got a great start programming in this chapter! We started by building a real project with PB. Then we used IB and Objective-C to build user interface objects, create and customize our own class, and connect these user interface objects with an object of our new class. We also learned a little more about Objective-C and some AppKit classes, and a lot about the files that PB generates. In the process, we used four important operations that IB can perform on classes: Subclass, Instantiate, Read Files, and Create Files. These operations were all found in the Classes menu in IB (some of these operations can be performed in ways other than using the menu commands).

These operations are the basic building blocks that you will use to create your own applications, although the order in which you use them will vary from project to project. Typically, the steps for creating an application are the following:

In the next chapter, we’ll add an About box (dialog) and some icons to our Calculator application, and we’ll find out how to increase the efficiency of a Cocoa application by using separate nib files.