Swift ios check if remote push notifications are enabled in ios9 and ios10

Question

How can I check if the user has enabled remote notifications on ios 9 or ios 10?

If the user has not allowed or clicked No I want to toggle a message asking if they

Answer 1

in iOS11, Swift 4...

 UNUserNotificationCenter.current().getNotificationSettings { (settings) in
        if settings.authorizationStatus == .authorized {
            // Already authorized
        }
        else {
            // Either denied or notDetermined
            UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .sound, .badge]) {
                (granted, error) in
                  // add your own 
                UNUserNotificationCenter.current().delegate = self
                let alertController = UIAlertController(title: "Notification Alert", message: "please enable notifications", preferredStyle: .alert)
                let settingsAction = UIAlertAction(title: "Settings", style: .default) { (_) -> Void in
                    guard let settingsUrl = URL(string: UIApplicationOpenSettingsURLString) else {
                        return
                    }
                    if UIApplication.shared.canOpenURL(settingsUrl) {
                        UIApplication.shared.open(settingsUrl, completionHandler: { (success) in
                        })
                    }
                }
                let cancelAction = UIAlertAction(title: "Cancel", style: .default, handler: nil)
                alertController.addAction(cancelAction)
                alertController.addAction(settingsAction)
                DispatchQueue.main.async {
                    self.window?.rootViewController?.present(alertController, animated: true, completion: nil)

                }
            }
        }
    }