iOS 7 Programming Cookbook

1.9. Presenting and Managing Views with UIViewController

Problem

You want to switch among different views in your application.

Solution

Use the UIViewController class.

Discussion

Apple’s strategy for iOS development was to use the model-view-controller (MVC) division of labor. Views are what get displayed to users, while the model is the data that the app manages, or the engine of the app. The controller is the bridge between the model and the view. The controller, or in this case, the view controller, manages the relationship between the view and the model. Why doesn’t the view do that instead? Well, the answer is quite simple: the view’s code would get messy, and that design choice would tightly couple our views with the model, which is not a good practice.

View controllers can be loaded from .xib files (for use with Interface Builder), or simply be created programmatically. We will first have a look at creating a view controller without a .xib file.

Xcode helps us create view controllers. Now that you have created an application using the Empty Application template in Xcode, follow these steps to create a new view controller for your app:

1. In Xcode, select the File menu and then choose New → New File...

2. In the New File dialog, make sure iOS is the selected category on the left and that Cocoa Touch is the chosen subcategory. Once you’ve done that, select the New Objective-C class item on the righthand side and press Next, as shown in Figure 1-24.

Figure 1-24. New Objective-C subclass

1. On the ...