title: Handling AutoLayout constraint animation differences in iOS 10?
body: <p>I've noticed that in iOS 10 Beta 5 (about to try Beta 6), AutoLayout constraint animation behaves a bit differently.</p>
  
  <p>For example, this approach does not work the same as it did in previous iOS releases:</p>
  
  <pre><code>[view addConstraints:@[constraints...]];
  
  [view setNeedsUpdateConstraints];
  [view layoutIfNeeded];
  
  [UIView animateWithDuration:...
  {
      /* adjust constraint here... */
      [view layoutIfNeeded]; // Only the adjusted constraints since previous layoutIfNeeded() call should animate change with duration.
  
  } completion:{ ... }];
  </code></pre>
  
  <p>... In my testing, the constraints initially added with <code>addConstraints()</code> will <strong>also</strong> animate in iOS 10 with the UIView <code>animateWithDuration()</code> block... which is causing some funky/undesirable behavior so far.</p>
  
  <p>For example, setting the left/right constraints in the array (but the vertical constraints in the block) <strong>causes the entire view to animate onto the screen diagonally</strong> with this approach... which is totally incorrect.</p>
  
  <p>Does anyone know how to do this correctly for both iOS 9 (and below), as well as 10?</p>