How to Zoom In/Out Photo on double Tap in the iPhone WWDC 2010 - 104 PhotoScroller

Question

I am going through the Sample code of iPhone WWDC 2010 - 104 PhotoScroller App. It\'s working great with my project related images (PDF Page Images)

but I am struggl

Answer 1

This appears to work using convertRect:fromView: and zoomToRect:animated::

-(void)tap:(UITapGestureRecognizer *)tapGestureRecognizer
{
    CGFloat zoomeScaleMultiplier = 0.5;
    UIScrollView *scrollView = (UIScrollView *) tapGestureRecognizer.view;
    UIView *zoomableView = [scrollView.delegate viewForZoomingInScrollView:scrollView];

    CGRect rect = scrollView.bounds;
    rect.origin = CGPointZero;

    CGAffineTransform transform = CGAffineTransformMakeScale(zoomeScaleMultiplier, zoomeScaleMultiplier);
    rect = CGRectApplyAffineTransform(rect, transform);

    rect.origin = [tapGestureRecognizer locationInView:scrollView];

    rect = CGRectOffset(rect, CGRectGetWidth(rect)/-2., CGRectGetHeight(rect)/-2.);

    rect = [zoomableView convertRect:rect fromView:scrollView];

    [scrollView zoomToRect:rect animated:YES];
}