UIScrollView: paging horizontally, scrolling vertically?

Question

How can I force a UIScrollView in which paging and scrolling are on to only move vertically or horizontally at a given moment?

My understanding is that

Answer 1

I used following method to solve this problem, hope it helps you.

First define following variables in your controllers header file.

CGPoint startPos;
int     scrollDirection;

startPos will keep the contentOffset value when your delegate receives scrollViewWillBeginDragging message. So in this method we do this;

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
    startPos = scrollView.contentOffset;
    scrollDirection=0;
}

then we use these values to determine users intended scroll direction in scrollViewDidScroll message.

- (void)scrollViewDidScroll:(UIScrollView *)scrollView{

   if (scrollDirection==0){//we need to determine direction
       //use the difference between positions to determine the direction.
       if (abs(startPos.x-scrollView.contentOffset.x)

finally we have to stop all update operations when user end dragging;

 - (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
    if (decelerate) {
       scrollDirection=3;
    }
 }