Programming iOS 6, 3rd Edition

Configuring and Displaying a Popover

To display a popover, you’ll need a UIPopoverController, along with a view controller (UIViewController) whose view the popover will contain. UIPopoverController is not itself a UIViewController subclass. The view controller is the UIPopoverController’s contentViewController. You’ll set this property initially through UIPopoverController’s designated initializer, initWithContentViewController:. Subsequently, if you like, you can swap out a popover controller’s view controller (and hence its contained view) by calling setContentViewController:animated:.

Here’s how the UIPopoverController for the first popover in Figure 22-1 is initialized. I have a UIViewController subclass, NewGameController. NewGameController’s view contains a grouped table (whose code I showed you in Chapter 21) and a UIPickerView (see Chapter 11 and Chapter 25), and is itself the data source and delegate for both. I instantiate NewGameController and use this instance as the root view controller of a UINavigationController, giving its navigationItem a leftBarButtonItem (Done) and a rightBarButtonItem (Cancel). I don’t really intend to do any navigation, but the navigation controller’s navigation bar is a convenient way of adding the two buttons to the interface. That UINavigationController then becomes a UIPopoverController’s view controller:

NewGameController* dlg = [NewGameController new]; UIBarButtonItem* b = [[UIBarButtonItem alloc] initWithBarButtonSystemItem: UIBarButtonSystemItemCancel ...