Zoom simultaneously in two UIImageView - objective-c

Question

I need to have two UIImageView, both with zoom enabled, (I can use the typical UISCrollView technique) and whenever I zoom in in one of them will result to zoom in the other as well, in the same point and with the same zoom.
Here's an explicative video: https://youtu.be/Ft-Dt3fx3z8?t=29s
Do you know any solution?
Thanks

Answer 1

I will answer my own question, first solution zooming async without scrolling
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
if (scrollView == _scrollView1)
return self.imageView1;
else
return self.imageView2;
}
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale
{
if (scrollView == _scrollView1){
[_scrollView2 setZoomScale:scale animated:YES];
[_scrollView2 setContentOffset:_scrollView1.contentOffset animated:YES];
}
else if (scrollView == _scrollView2){
[_scrollView1 setZoomScale:scale animated:YES];
[_scrollView1 setContentOffset:_scrollView2.contentOffset animated:YES];
}
}
Second, better solution with real time zooming and scrolling (viewForZoomingInScrollView is still needed)
- (void)matchScrollView:(UIScrollView *)first toScrollView:(UIScrollView *)second {
CGPoint offset = first.contentOffset;
offset.x = second.contentOffset.x;
offset.y = second.contentOffset.y;
[first setContentOffset:offset];
[first setZoomScale:second.zoomScale];
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
if([scrollView isEqual:_scrollView1]) {
[self matchScrollView:_scrollView2 toScrollView:_scrollView1];
} else {
[self matchScrollView:_scrollView1 toScrollView:_scrollView2];
}
}