title: Dynamic constraints update
body: <p>In my project there is a specific stuff I'd like to implement but for doing that I might change constraints of views dynamically. Let's say I've got a UIView instance and a UILabel one. The picture below shows how it looks like. (The picture is a little bit huge, it's all iPhone 6 you know ;P)</p>
  
  <p><img src="https://i.stack.imgur.com/CPoK0.png" alt="enter image description here"></p>
  
  <p>It's initially being like that. But when a view appeared I make calculations (to determine whether to change a container's height or not) and apply them. If the container (a grey colored view) is necessary to be decreased an app does it and finally we might get something like... </p>
  
  <p><img src="https://i.stack.imgur.com/YsSXG.png" alt="enter image description here"></p>
  
  <p>I wish it could work exactly the same I just described but... It does not. Instead, it goes like... </p>
  
  <p><img src="https://i.stack.imgur.com/nsCIY.png" alt="enter image description here"></p>
  
  <p>So the container is changed in its height but the label right below is at the same place even though there were constraints. So I wonder how to dynamically update views locations according to their updated sizes.</p>
  
  <p>Thank you in advance! </p>