title: Animating only the image in UIBarButtonItem
body: <p>Ive seen this effect in 2 apps and I REALLY want to find how to do it.</p>
  
  <p>The animation is in a UIBarButtonItem, and is only to the image. The image is a + symbol, and it rotates to a X.</p>
  
  <p>If you want to see the effect you have to start a conversation with someone and next to the text input theres the + button for images and emoji's. Or heres a video of the effect in another app, after he taps the bar button you see it rotate to a X, <a href="http://www.youtube.com/watch?v=S8JW7euuNMo" rel="nofollow">http://www.youtube.com/watch?v=S8JW7euuNMo</a>.</p>
  
  <p>I have found out how to do the effect but only on a UIImageView, I have to turn off all the autoresizing and the view mode has to be centered, then apply the rotation transform to it. I have tried many ways of trying to have it work in a bar item and so far the best way is adding a image view instance, then setting it up and setting the view mode centered and autoresizing off and then using that image view for a custom bar item view. But when i do this, the effect works except while its doing it, the image will go off to the side a little bit instead of staying where it already is. Ive tried getting the center before the animation and set it during the animation but that doesnt do anything.</p>