How do I get notification when a Facebook friend installed an app

I am writing an iOS app and authentication is handled by Facebook SDK. I want to get an notification in my App when a friend of mine starts using the app. How do I retrieve this information from API ?

Solution

You can authorize users with user_friends, use /me/friends to get all the friends who authorized the App too and then send a message to all the friends in the list if the user is new.