You’re using the Model View Controller pattern

Model View Controller (MVC) is a pattern that is discussed at length in Head First Design Patterns. You see it used a lot with GUI applications, and it’s all over the Cocoa Touch framework. The short version is that as much as possible, you want to separate out your logic from your view and data. It’s especially key when you want to write one set of logic to support both iPhone and iPad UIs, which we’ll do later in the book.