title: Add UIImage on top of another UIImage
body: <p>i have 2 images: first one is the user personal image, the second one is an icon (badge).</p>
  
  <p>i want to add the second uiimage (icon) on the bottom left corner of the first uiimage (user's image) and save them into a new Uiimage.</p>
  
  <p>thanks</p>