Zoom Scrollview

gistfile1.m

- (void)scrollViewDoubleTapped:(UITapGestureRecognizer*)recognizer {
    // 1
    CGPoint pointInView = [recognizer locationInView:self.imageView];
 
    // 2
    CGFloat newZoomScale = self.scrollView.zoomScale * 1.5f;
    newZoomScale = MIN(newZoomScale, self.scrollView.maximumZoomScale);
 
    // 3
    CGSize scrollViewSize = self.scrollView.bounds.size;
 
    CGFloat w = scrollViewSize.width / newZoomScale;
    CGFloat h = scrollViewSize.height / newZoomScale;
    CGFloat x = pointInView.x - (w / 2.0f);
    CGFloat y = pointInView.y - (h / 2.0f);
 
    CGRect rectToZoomTo = CGRectMake(x, y, w, h);
 
    // 4
    [self.scrollView zoomToRect:rectToZoomTo animated:YES];
}