iOS 5 Programming Cookbook

2.12. Presenting Multiple View Controllers with UITabBarController

Problem

You would like to give your users the option to switch from one section of your app to another, with ease.

Solution

Use the UITabBarController class.

Discussion

If you use your iPhone as an alarm clock, you have certainly seen a tab bar. Have a look at Figure 2-34. The bottom icons labeled World Clock, Alarm, Stopwatch, and Timer are parts of a tab bar. The whole black bar at the bottom of the screen is a tab bar and the aforementioned icons are tab bar items.

A tab bar is a container controller. In other words, we create instances of UITabBarController and add them to the window of our application. For each tab bar item, we add a navigation controller or a view controller to the tab bar, and those items will appear as tab bar items. A tab bar controller contains a tab bar of type UITabBar. We don’t create this object manually. We create the tab bar controller and that will create the tab bar object for us. To make things simple, remember that we instantiate a tab bar controller and set the view controllers of that tab bar to instances of either UIViewController or UINavigationController if we intend to have navigation controllers for each of the tab bar items (aka, the view controllers set for the tab bar controller). Navigation controllers are of type UINavigationController that are subclasses of UIViewController. Therefore, a navigation controller is a view controller but view controllers of type UIViewController ...