title: Animate a UITextField when changing from hidden to visible using AutoLayout
body: <p>I have a UITextField that is set to hidden, when I click the search button I want to make it visible but I want to create an animation like a slide-in, is it possible to recreate this effect if i'm using autoLayout?</p>
  
  <p>The code I used for the animation is the current (it creates a fade-in effect):</p>
  
  <pre><code>if(!currentSrcState)
      {
          _searchField.hidden = NO;
          [UIView animateWithDuration:0.3
                                delay:0.0
                              options:UIViewAnimationOptionTransitionCurlDown
                           animations:^ {
                               _searchField.alpha = 1.0;
                           }
                           completion:nil];
          currentSrcState = YES;
      }
      else
      {
          [UIView animateWithDuration:0.3
                                delay:0.0
                              options:UIViewAnimationOptionTransitionCurlDown
                           animations:^ {
                               _searchField.alpha = 0;
                           }
                           completion:^(BOOL finished){
                               _searchField.hidden = YES;
                           }];
  
          currentSrcState = NO;
      }
  </code></pre>
  
  <p>What I want to acheive is that when the <code>_searchField</code> is hidden the constraint gets recalculated in order to move what is under the searchField up</p>