title: Width UIButton auto layout
body: <p><a href="https://i.stack.imgur.com/ZJI5c.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ZJI5c.png" alt="enter image description here"></a></p>
  
  <p>I want the "Connexion" button to be of the same aspect ratio of what it looks on the image but I don't figure it out. With all that I read on auto layout on the web I got very confused with it.</p>
  
  <p>If someone can explain to me what constraints I have to add to have this result and most importantly <strong>why</strong> ?</p>