iPhone UIScrollView / setContentOffset weirdness

Posted by bibac on Stack Overflow See other posts from Stack Overflow or by bibac
Published on 2010-01-30T16:47:37Z Indexed on 2010/06/03 18:04 UTC
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Hi,

I have a weird issue with setContentOffset which I don't seem to be able to solve: I'm trying to build an "endless" scroll view, so I'd like to reset the content offset at a certain position. With the code below setContentOffset will be called at x=160px. If I drag the scroll view my log looks like this:

offset: 158

offset: 159

offset: 160

offset: 80

offset: 160

What happens is that my setContentOffset (to 80) is performed, when I keep on dragging UIScrollView seem to have forgotten about it and continues at 160. Even weirder: When I set animated:YES it works. Maybe a timing issue? When I call setContentOffset from within scrollViewDidScroll, scrollViewDidScroll will be called again.

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
 NSInteger tileNo = floor(scrollView.contentOffset.x / 80);
 NSLog(@"offset: %f, tile: %d, lastTile: %d", scrollView.contentOffset.x, tileNo, lastTileNo);

 if (tileNo > lastTileNo) {
      [scrollView setContentOffset:CGPointMake(80, 0) animated:NO];
 }

 lastTileNo = tileNo;

}

Thanks for helping me out, Stephan

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