title: How to center both vertical and horizontal inside a UIStackView
body: <p>I have a simple <strong>UIImageView</strong> with <strong>50x50 size</strong>.
  If I had a UIView of size 100x100 and I wanted to center the image inside of it, all I have to do is set these
  <a href="https://i.stack.imgur.com/FBqwV.png" rel="noreferrer"><img src="https://i.stack.imgur.com/FBqwV.png" alt="enter image description here"></a></p>
  
  <p>But how do I do the same with a <strong>UIStackView of size 100x100</strong>?</p>
  
  <p><strong>EDIT</strong> i think i should have been more clear. The questions is, how do i center the image both vertically &amp; horizontally inside of the UIStackview ?</p>