AppDelegate.swift

 func application(_ app: UIApplication, open url: URL, options: [UIApplicationOpenURLOptionsKey : Any] = [:]) -> Bool {
        
     let handled = FBSDKApplicationDelegate.sharedInstance().application(app, open: url, sourceApplication: options[UIApplicationOpenURLOptionsKey.sourceApplication] as! String! , annotation: options[UIApplicationOpenURLOptionsKey.annotation])
        
        return handled
    }