Check whether a user removed the app from their respective account

Question

In application I'm trying to add user verification by sms, email, facebook and google login. It makes user more reliable.

So how could I check if user removed the app from their own fb/google account ? I will move the verification Item to non-verified section according to it. Is there any tricky side ?

Answer 1

Go to your App Settings and click on "Settings - Advanced". You will find the "Deauthorize Callback URL", it will get called whenever a user deauthorizes your Facebook App.