title: "Sign-in with facebook" code in Sencha ! to integrate in apps
body: <p>I am creating an app using Sencha and I need to integrate the facebook login in it . When i click on the "login in with facebook " button , if the user is not logged in facebook ,it should show a pop-up to enter facebook email-id and password, else if the user has already logged in it should just sign-in with facebook authentication. How do I implement this using sencha touch . Please help . It would be helpful if the code for this functionality is provided.Thanks</p>