title: Tell When a UIPageViewController is Scrolling (for Parallax Scrolling of an Image)
body: <p>I am trying to make an effect similar to that found in the new Yahoo weather app. Basically, each page in the <code>UIPageViewController</code> has a background image, and when scrolling through the page view, the Image's location only scrolls about half the speed. How would I do that? I thought I could use some sort of Delegate Method in the <code>UIPageViewController</code> to get the current offset and then update the images like that. The only problem is that I cannot find anyway to tell if the <code>UIPageViewController</code> is being scrolled! Is there a method for that? Thanks!</p>