Programming iOS 6, 3rd Edition

Page View Controller

A page view controller (UIPageViewController) has one or two child view controllers whose view(s) it displays within its own view. The user can then make a gesture (such as dragging) to navigate, revealing the view of a different view controller or pair of view controllers, analogously to the pages of a book.

Page view controllers were introduced in iOS 5, and are a great addition to the repertoire of built-in view controllers. Before iOS 5, I was accomplishing the same sort of thing in my flashcard apps by means of a scroll view (Chapter 20); the code was complex and tricky. With a page view controller, I was able to make my app’s code far simpler.

To create a UIPageViewController, initialize it with initWithTransitionStyle:navigationOrientation:options:. Here’s what the parameters mean:

transitionStyle:

Your choices are:

• UIPageViewControllerTransitionStylePageCurl (the old page curls off of, or onto, the new page)
• UIPageViewControllerTransitionStyleScroll (the new page slides into view while the old page slides out).

navigationOrientation:

Your choices are:

• UIPageViewControllerNavigationOrientationHorizontal
• UIPageViewControllerNavigationOrientationVertical

options:

A dictionary. Possible keys are:

UIPageViewControllerOptionSpineLocationKey

The position of the spine (the pivot line around which page curl transitions rotate); relevant only if you’re using the page curl transition. The value is an NSNumber wrapping one of the following:

• UIPageViewControllerSpineLocationMin ...