Question

I’m on Monotouch 5.2.6 and iOS SDK 5.0.1.

I have a UIPageViewController that is a child container of another view controller.
It is created like this:

pageViewController = new UIPageViewController (UIPageViewControllerTransitionStyle.PageCurl, UIPageViewControllerNavigationOrientation.Horizontal, UIPageViewControllerSpineLocation.Min);
    this.AddChildViewController (pageViewController);
    pageViewController.DidMoveToParentViewController (this);
    this.viewCurrentMode.AddSubview (pageViewController.View);

If I rotate the device (Simulator), I get this exception in UIApplication.SendEvent():

Objective-C exception thrown. Name: NSInternalInconsistencyException
Reason: The number of provided view controllers (1) doesn’t match the
number required (2) for the requested spine location
(UIPageViewControllerSpineLocationMid)

The spine location is NOT “mid” but “min”. Any ideas?

Answer 1

True, you have initialized the UIPageViewController with “Min” as spine location. However, you need to implement a delegate for your page controller and override the GetSpineLocation method:

public override UIPageViewControllerSpineLocation GetSpineLocation (UIPageViewController pageViewController, UIInterfaceOrientation orientation)
{

    //return spine location according to interface orientation and whatever
    //criteria you prefer

}

Or, assign a method to its GetSpineLocation property (MonoTouch heaven! ):

pageViewController.GetSpineLocation = (p, o) => return <spinelocation>;

Still, it looks a bit unexpected behavior. I assume that the default implementation of the native pageViewController:spineLocationForInterfaceOrientation: method returns “Mid” when the device rotates to landscape (although could not find info in Apple docs). Anyway, you must override the above method to get it right.