title: Facebook login on iPhone. Authenticate with Rails Backend (Devise+Omniauth)
body: <p>I am trying to implement a facebook user authentication in my iOS6 App through my Rails Backend running with Devise using omniauth. I am looking for a step by step guide how to setup my API and Devise + Authentication.</p>
  
  <p>I only have a only have a rough knowledge about how to do that.</p>
  
  <ol>
  <li>(on App) check if the user signs in on his facebook on iPhone</li>
  <li>iPhone is authenticated client sided on Facebook. FB passes me his mobile auth token</li>
  <li>I send my auth token or auth hash to my rails backend via API RESTful SSL.</li>
  <li>Rails receives the Token and checks if it is valid. ( What command uses the least traffic against FB Graph API? with Koala Gem)</li>
  <li>If valid. Check if the user already exists. If not, create a new user.</li>
  <li>Create a new session.</li>
  </ol>
  
  <p>Is this correct?</p>
  
  <p>Are there any good examples?</p>
  
  <p>Thank you very much.</p>