title: Autolayout animate constraint does not animate subviews
body: <p>I have a UIView which has a UILabel as subview in it.</p>
  
  <p>Now I change the width of the UIView with an animation (changing constant property of constraint) and call layoutIfNeeded in UIView animate...)</p>
  
  <p>The view is resizing normal, <strong>but</strong> the UILabel (subview) changes the font size to the 'end'-size but didn't animate correctly like the uiview.</p>
  
  <p>According to the WWDC 2012 session the subviews should animate if only the constant of the superview gets changed.</p>
  
  <p>The UILabel has a minimum font scale of 0,1 which is less then the font has to resize.</p>