title: How do I align a label vertical center in XCode 6
body: <p>Whenever I add constraints to the height and width of my UILabel, the text will then jump to the top of the controller. </p>
  
  <p>How can I <em>vertically</em> center the UILabel in the ViewController?
  <img src="https://i.stack.imgur.com/69QGi.png" alt="Image of contstraints"></p>
  
  <p><img src="https://i.stack.imgur.com/DbEAY.png" alt="enter image description here"></p>