Question

I have custom view in my application which can be scrolled by the user. This view, however, does not inherit from UIScrollView. Now I want the user to be able to scroll this view to the top, just as any other scrollable view allows. I figured that there is no direct way to do so.

Google turned up one solution: http://cocoawithlove.com/2009/05/intercepting-status-bar-touches-on.html This no longer works on iOS 4.x. That’s a no-go.

I had the idea of creating a scrollview and keeping it around somewhere, just to catch it’s notifications and then forward them to my control. This is not a nice way to solve my problem, so I am looking for “cleaner” solutions. I like the general approach of the aforementioned link to subclass UIApplication. But what API can give me reliable info?

Are there any thoughts, help, etc…?

Edit: Another thing I don’t like about my current solution is that it only works as long as the current view does not have any scroll views. The scroll-to-top gesture works only if exactly one scroll view is around. As soon as the dummy is added (see my answer below for details) to a view with another scrollview, the gesture is completely disabled. Another reason to look for a better solution…

Answer 1

So this is my current solution, which works amazingly well. But please come with other ideas, as I don’t really like it…

• Add a scrollview somewhere in your view. Maybe hide it or place it below some other view etc.
• Set its contentSize to be larger than the bounds
• Set a non-zero contentOffset
• In your controller implement a delegate of the scrollview like shown below.

By always returning NO, the scroll view never scrolls up and one gets a notification whenever the user hits the status bar. The problem is, however, that this does not work with a “real” content scroll view around. (see question)

- (BOOL)scrollViewShouldScrollToTop:(UIScrollView *)scrollView
{
    // Do your action here
    return NO;
}