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

I would do this:

Objective-C

for (UIView *v in self.pageViewController.view.subviews) {
    if ([v isKindOfClass:[UIScrollView class]]) {
        ((UIScrollView *)v).delegate = self;
    }
}

and implement this protocol

- (void)scrollViewDidScroll:(UIScrollView *)scrollView

Swift

for view in self.pageViewController.view.subviews {
  if let scrollView = view as? UIScrollView {
    scrollView.delegate = self
  }
}

and implement this protocol

func scrollViewDidScroll(scrollView: UIScrollView)