UIPageViewController as application's root controller

Question

I'm using UIPageViewController for the first time. It's of course, iOS5 and I'm comfortable with ARC. I'm not using Storyboards.

In all the piecemeal examples I see, the UIPageViewController never "owns" the screen. It is always the child of some other view controller. Is this a requirement? I want to make it the root controller of my app, much like is commonly done with UINavigationController. I'm trying to set it all up programmatically, but all I get is an empty page view controller, with no content in it.

Here's how the app starts off (all code here is in my app delegate class):

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

    [self configureLoggers];
    [self applyAppearanceProxySettings];
    [self configureDataStore];
    [self configureNavigationController];
    [self configurePageController];    // <-- this is where we do the page view controller setup, shown next.

    self.window.rootViewController = self.pageController;
    [self.window makeKeyAndVisible];

    log4Info(@"Application completed launching.");

    return YES;
}

And that method mentioned in the code above, that does the setup for the Page View Controller:

- (void)configurePageController {
    CCFrontCoverViewController *frontCoverViewController = [[CCFrontCoverViewController alloc] initWithNibName:nil bundle:nil];

    NSDictionary *options = [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:UIPageViewControllerSpineLocationMin]
                                                    forKey:UIPageViewControllerOptionSpineLocationKey];

    self.pageController = [[UIPageViewController alloc] initWithTransitionStyle:UIPageViewControllerTransitionStylePageCurl
                                                      navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal
                                                                    options:options];

    self.pageController.delegate = self;
    self.pageController.dataSource = self;
    self.pageController.view.backgroundColor = [UIColor redColor]; // So we know we're missing content because red shows through.

    NSArray *pageViewControllers = [NSArray arrayWithObjects:frontCoverViewController, self.navigationController, nil];
    [self.pageController setViewControllers:pageViewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];
}

I've also put logging in the two data source callback methods, and they don't even get called.

When this is run, I just get a blank red screen. Again, there's no storyboard involved. What am I missing?

Answer 1

I am able to use a UIPageViewController as the root view controller in a sample project provided that:

• The UIPageViewController is initialized properly with a valid spine location.
• The UIPageViewController's doubleSided property is set (consistent with the spine location).
• The UIPageViewController's viewControllers array is set (again, consistent with the spine location and doubleSided property).

It looks like you haven't set doubleSided to YES in your code (since your viewControllers array has two items in it). Does adding that before you set the viewControllers array fix your problem?

EDIT: Just for posterity, in the UIPageViewController docs there is a chart in the description of the setViewControllers:direction:animation:completion: method showing the number of view controllers allowed for all valid combinations of spine location and doubleSided.