title: How to crop an image with a selectable area in swift 4 or later?
body: <p>I need some help with a function that I'd like to implement in my app.
  I have a view with an image view with content mode in Aspect Fit. When I get an image from my library I would like to crop an area with an adjustable rectangle creating a new image.
  I've looked for some exemple or online tutorial but I did not succeed.
  Can anyone help me with that?
  Here are the images from my View.  </p>
  
  <p><img src="https://i.stack.imgur.com/VBOWR.png" alt="This is my view in the Storyboard">.  </p>
  
  <p><img src="https://i.stack.imgur.com/xg1Oh.png" alt="And here is my view in Simulator"></p>