swapping images using pan gesture

问题:

I have multiple UIImageView added into the main view, each UIImageView is displayed in its own parent UIView for cropping purpose, each UIImageView is also attached to a PanGestureRecognizer.

I am curious on how to implement both pan gesturerecgonizer and also allow image swap by dragging one image (A) to hover over the other image (B) and hold, then the image A and B will be swapped (so A is now displayed in old B's UIView).

This is something like the iPhoto app just implemented.

Any ideas?

回答1:

• Implement the pan gesture

• In the method which handles the pan gesture check if the frames of two imageview's intersect by using CGRectIntersectsRect.

  if ([gestureRecognizer state] == UIGestureRecognizerStateEnded)
  {
  if(CGRectIntersectsRect(frame1,frame2))
         // Swap both the imageview's
  }