title: how to overlap image on another images while dragging it in iOS?
body: <p>I have created JIGSAW game. In that I've split image into 3X3 matrix and display on screen (i.e <code>[self.view addSubView:imageview]</code> like this I added all 9 image tiles).
  Now for solving game when I drag one image tile to another image tile sometimes it goes over the image or sometimes under the image (like the default behavior of iOS first image added to view appears under remaining all images and last added image appears on top when user drag image see in attached images)
  Now I want when I drag any image tile it must be appear on top of remaining images.
  Same as last added image appears on top.</p>
  
  <p><img src="https://i.stack.imgur.com/Xy0sQ.png" alt="enter image description here"></p>