func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

    FBSDKApplicationDelegate.sharedInstance().application(application, didFinishLaunchingWithOptions: launchOptions)
    return true
}


func application(_ application: UIApplication, open url: URL, sourceApplication: String?, annotation: Any) -> Bool {

    return FBSDKApplicationDelegate.sharedInstance().application(application, open: url, sourceApplication: sourceApplication, annotation: annotation)
}

 
@available(iOS 9.0, *)
func application(_ app: UIApplication, open url: URL, options: [UIApplicationOpenURLOptionsKey : Any]) -> Bool {

    return FBSDKApplicationDelegate.sharedInstance().application(app, open: url, sourceApplication: options[UIApplicationOpenURLOptionsKey.sourceApplication] as? String, annotation: options[UIApplicationOpenURLOptionsKey.annotation])
}

 
facebookManager.tryAuthenticate(fromViewController: self, success:{ facebookToken in

    self.getProfileIfNeeded()

}) { error in

    print("Error: \(String(describing: error?.localizedDescription))")
}


private func getProfileIfNeeded(){

    facebookManager.fetchLoggedUserInfo(successBlock: { (userInfo) in

        print("\(String(describing: userInfo))")

    }) { (error) in
        print("Error: \(String(describing: error?.localizedDescription))")
    }
}