Connect two UIScrollView's together

Question

Here\'s a tricky iPhone problem I\'ve been working on. I have three UIScrollViews on a page, one that only scrolls horizontally, one that only scrolls vertically, and one th

Answer 1

I think the simplest way would be to add a delegate to your scrollviews which implement the following method:

- (void)scrollViewDidScroll:(UIScrollView *)scrollView

Then you can check the contentOffset to check by how much the scrollview did actually scroll, and update the main scrollview accordingly.

Answer 2

You need to extend UIScrollView for all three uses on your screen and override the touchesMoved:withEvent: methods to call the other ones (make sure you don't end up with circular code that ends up calling itself again!).

So, for example the code in the two-way scrolling item could be based on this:

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    [horizontalScrollview touchesMoved:touches withEvent:event];
    [verticalScrollview touchesMoved:touches withEvent:event];
}

by using some additional variable (eg ControllerLastTouched) you can check that before calling the other two touchesMoved:withEvent: methods.

This should enable you to do the "cloning" you were talking about...