How to connect to Facebook using the downloaded Facebook app, and not the embeeded Facebook connect. This is done for example with Rockmelt app.
What seems to be done, is to launche a third party app using the url like (fb:some paramaeters) and having a callback url with your app (myapp://authentification parameter ).
The interest of this is that if you are already logged on facebook, you just need to approve or not your app.
What is missing, is what are the parameters to acheive this with the downloaded facebook app.
Just use the supplied Facebook Connect library as it handles all this for you. FBConnect by default will use single sign on either via the browser or the facebook app if already installed.
You can examine the source code of the FBConnect library to see how this is done if you wish, but I’d suggest that re-inventing the wheel is perhaps not the best way to go.