Content pushed down in a UIPageViewController with UINavigationController

UPDATE 2

I've been running and testing my app in the iOS Simulator using a 4-inch device. If I run using a 3.5-inch device the label doesn't jump. In my .xib, under Simulated Metrics, I have it set as Retina 4-inch Full Screen. Any idea why I'm only seeing this problem on a 4-inch device?

UPDATE 1

In IB, if I choose "Navigation Bar" in Simulated Metrics, my label still jumps. The only way I can get my label to render correctly on the first screen is to not set a navigation controller as my window's root view controller.

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My window's rootViewController is being set to a UINavigationController whose rootViewController has a UIPageViewController embedded.

When my app loads, the initial view is presented with it's content pushed down a bit, roughly the same size as a navigation bar. When I scroll the pageViewController, the content jumps up to where it was placed in the nib, and all other viewControllers loaded by the pageViewController are fine.

In my appDelegate:

self.window.rootViewController = [[UINavigationController alloc] initWithRootViewController:[ContainerViewController new]];

In ContainerViewController:

- (void)viewDidLoad {

    [super viewDidLoad];

    self.pvc = [[UIPageViewController alloc] initWithTransitionStyle:UIPageViewControllerTransitionStyleScroll
                                               navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal
                                                             options:nil];
    self.pvc.dataSource = self;
    self.pvc.delegate = self;
    DetailViewController *detail = [DetailViewController new];
    [self.pvc setViewControllers:@[detail]
                       direction:UIPageViewControllerNavigationDirectionForward
                        animated:false
                      completion:nil];

    [self addChildViewController:self.pvc];
    [self.view addSubview:self.pvc.view];
    [self.pvc didMoveToParentViewController:self];
}

Solution 1:

So I'm adding another answer after further development and I finally think I figured out what's going on. Seems as though in iOS7, UIPageViewController has its own UIScrollView. Because of this, you have to set automaticallyAdjustsScrollViewInsets to false. Here's my viewDidLoad now:

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.automaticallyAdjustsScrollViewInsets = false;

    DetailViewController *detail = [[DetailViewController alloc] init];
    [self setViewControllers:@[detail]
                   direction:UIPageViewControllerNavigationDirectionForward
                    animated:false
                  completion:nil];
}

No need to put anything in viewWillLayoutSubviews (as one of my previous answers suggested).

Solution 2:

This is definitely being caused by automaticallyAdjustsScrollViewInsets, as other posters (including @djibouti33). However, this property is strange in two ways:

1. It must be set on a UINavigationController. If you set it on a child controller that's managed by a UINavigationController, it won't have any effect. 1
2. It only applies when a scroll view is at index zero in a controller's subviews. 2

These two caveats should explain the intermittent problems experienced by others in the thread.

TLDR: A workaround that I went with is adding a dummy view to the UIPageViewController at index zero, to avoid the setting applying to the scrollView within the page controller, like this:

pageViewController.view.insertSubview(UIView(), atIndex: 0) // swift

[pageViewController.view insertSubview: [UIView new] atIndex: 0]; // obj-c

Better would be to set the contentInset on the scroll view yourself, but unfortunately the UIPageViewController doesn't expose the scroll view.