title: Scan Fb QRCode to login app
body: <p>I'm creating new application that scan Facebook QR Code to login.
  The result will same as u click "Login with Facebook" in website.
  But my app is use Facebook QR Code to do that. My app will scan the QR Code from your phone
  then it will login to my app by Facebook account. Now i'm done the scan code but don't know how to use that code to login as Facebook account. Please help me. Thank you.</p>