title: Can constraints in Xcode 6 be dynamic?
body: <p>I'm biting the bullet and have begun using auto layout. Not as difficult to get used to than I feared. I am having trouble with this though.</p>
  
  <p>Is it possible for view 2 to 'anchor' to the bottom of view 1.. UNLESS view 1 is hidden, in which case it should anchor to the top of the containing view? How would I set constraints for this?</p>
  
  <p>If View1.hidden = NO:</p>
  
  <p><img src="https://i.stack.imgur.com/y0yRz.png" alt="enter image description here"></p>
  
  <p>If View1.hidden = YES:</p>
  
  <p><img src="https://i.stack.imgur.com/mSzZH.png" alt="enter image description here"></p>