title: How to merge two UIImages?
body: <p>I am trying to merge two different images and create a new one. This is the way I would like to do:
  I have this image (A):</p>
  <p><a href="https://i.stack.imgur.com/g70aw.png" rel="noreferrer"><img src="https://i.stack.imgur.com/g70aw.png" alt="polaroid" /></a></p>
  <p>It's a PNG image and I would like to merge this one with another image (B) which I took from the phone to create something like this:</p>
  <p><a href="https://i.stack.imgur.com/UTxVP.png" rel="noreferrer"><img src="https://i.stack.imgur.com/UTxVP.png" alt="polaroid merged" /></a></p>
  <p>I need a function who merge A with B creating C. The size must remain from the A image and the image B should auto adapt the size to fit into the polaroid (A). Is it possible to do that? Thank for your help!</p>
  <p><strong>UPDATE</strong>
  Just one thing, the image (A) is a square and the image i took is a 16:9, how can i fix that?? If i use your function the image (B) that i took become stretched!</p>