UIButton location while zooming a UIScrollView

Question

Hello:

I have a "world view," so to speak, that consists of a large, zoomable area on a UIScrollView. I want several buttons to retain their world location when I pinch to zoom, much like pins in Google Maps do. The code I have been trying (I have been coding for hours, but I think it sounds right...although I may be just burned out) is:

- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
    CGPoint center = button.center;
    center.y = center.y * scrollView.zoomScale;
    center.x = center.x * scrollView.zoomScale;
    button.center = center;
    NSLog(@"Button coordinates are %f, %f, zoomScale is %f", button.center.x, button.center.y, scrollView.zoomScale);
}

Can anyone see what I'm doing wrong?

Thanks in advance!

Answer 1

I solved this by setting the CGPoint 'center' only once, on view load, and then calculating a new center point based off of the original location.

- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
    CGPoint newCenter = center; //center is set at load time, and only once
    newCenter.y = center.y * scrollView.zoomScale; //new center is calculated on original position
    newCenter.x = center.x * scrollView.zoomScale;
    button.center = newCenter;

    NSLog(@"Button coordinates are %f, %f, zoomScale is %f", button.center.x, button.center.y, scrollView.zoomScale);
}

Sorry about mistagging the question, Peter.