title: use facebook iOS client authorization on own to server
body: <p>I am using facebook SSO in my iOS app and that works alright.
  Now I would like to use that information - the user being verified against facebook with his uid - on my server backend. But how can I - securely - pass this information to the server?</p>
  
  <p>My guess is that I'd need to send the uid and probably the authToken I got from facebook to my server? Could someone outline a general approach to that?</p>
  
  <p>Even though it shouldn't really matter for my question, my server is running rails and devise for authentication. I also have facebook login working there separately, but I want to use the already done authentication from the client on the server. Confusing...</p>