title: ios - pinch/zoom an image, centered on touches
body: <p>I can get pinch/zoom functionality working like this:</p>
  
  <pre><code>- (void)twoFingerPinch:(UIPinchGestureRecognizer *)recognizer
  {
  
      if([recognizer state] == UIGestureRecognizerStateBegan) {
          _lastScale = 1.0;
      }
  
      CGFloat scale = 1.0 - (_lastScale - [recognizer scale]);
  
      CGAffineTransform currentTransform = self.imageForEditing.transform;
      CGAffineTransform newTransform = CGAffineTransformScale(currentTransform, scale, scale);
  
      [self.imageForEditing setTransform:newTransform];
  
      _lastScale = [recognizer scale];
  
  
  }
  </code></pre>
  
  <p>The problem is that the image zooms based on it's center, so if you first pan the image so that it's not centered, then pinch/zoom, it doesn't zoom into the area between the touches. I figure this must be a common issue that has been addressed and solved but I haven't been able to find a solution.</p>