iOS. How do I restrict UIScrollview scrolling to a limited extent? [duplicate]

Question

What is the best way to set limits on the left/right scrolling of a UIScrollView. I would have thought this would be easy but all my attempts have been unsuccessful.

So, to be clear, I need a solution that will allow me to programmatically limit the scrolling extent whenever I need to during the use of my app. This will most often be in response to changes in the data being displayed.

Thanks,
Doug

Answer 1

You can control the size of contents using contentSize property of scroll view. If that is not sufficient for you (e.g. you need to limit scroll area to some arbitrary region in the middle of your contents) you can force contentOffset to be in required limit in the delegate method of your scroll view.

Basically code may look like:

- (void) scrollViewDidScroll:(UIScrollView*)scroll{
    CGPoint offset = scroll.contentOffset;

    // Check if current offset is within limit and adjust if it is not
    if (offset.x < minOffsetX) offset.x = minOffsetX;
    if (offset.y < minOffsetY) offset.y = minOffsetY;
    if (offset.x > maxOffsetX) offset.x = maxOffsetX;
    if (offset.y > maxOffsetY) offset.y = maxOffsetY;

    // Set offset to adjusted value
    scroll.contentOffset = offset;
}

Answer 2

All you would need to do is change the content size for the scroll view with the following code.

[scrollView setContentSize:CGSizeMake(width, height)];