title: iOS how to center two view via PureLayout
body: <p>I want to center my UIImageView and UILabel like the pic below.
  I used a container to contain UIImageView and UILabel,but the container does not suit the width of UIImageView and UILabel.So I need to set the width of the container.Is there any method to solve the problem without set the width or calculate the view's width? Here's the picture:</p>
  
  <p><img src="https://i.stack.imgur.com/Zga6m.png" alt="MyLabel"></p>