how to check that user is logged in to facebook - php sdk
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How I can determine that user is logged in to facebook but not authenticated my facebook web application using php sdk. I know we have **$user = $facebook->getUser();** but this only check that user authenticated the app or not. I want something like **FB.getLoginStatus** 

 1. the user is logged into Facebook and has authenticated your application (connected)
 2. the user is logged into Facebook but has not authenticated your application (not_authorized)
 3. the user is not logged into Facebook at this time and so we don't know if they've authenticated your application or not (unknown)

Want to determine second condition using php sdk i.e. of not_authorized but logged in to facebook