Tell When a UIPageViewController is Scrolling (for Parallax Scrolling of an Image)

Question

I am trying to make an effect similar to that found in the new Yahoo weather app. Basically, each page in the UIPageViewController has a background image, and w

Answer 1

What you are looking for is called parallax scrolling, you can find several libraries that can help you with that.

Edit: Matt is right this is not an answer, only a hint. Anyway let's complete it:

For animating a background image that lay behind your UIPageViewController you should use the delegate methods that it offer:

-[id pageViewController:willTransitionToViewControllers:]
-[id pageViewController:didFinishAnimating:previousViewControllers:transitionCompleted:]

With these two methods you can calculate the percentage of the scrolling (you should store your controllers in your array to know at which controller you scrolled to and get the percentage)