Where to call NotificationCenter.default.addObserver() ? in my Xcode Game Project

I successfully call the following from my func application (AppDelegate), but when I toggle the Gamepad on/off, my selectors are not being called.

class GameScene: SKScene {

    func ObserveForGameControllers() {

    //  print("ObserveForGameControllers")

        NotificationCenter.default.addObserver(
                    self,
                    selector: #selector(connectControllers),
                    name: NSNotification.Name.GCControllerDidConnect,
                    object: nil)

        NotificationCenter.default.addObserver(
                    self,
                    selector: #selector(disconnectControllers),
                    name: NSNotification.Name.GCControllerDidDisconnect,
                    object: nil)

    }   // ObserveForGameControllers

}

My selectors look like this:

@objc func connectControllers() {}
@objc func disconnectControllers() {}

Someone recommended I call ObserveForGameControllers() from my class GameScene, like so

override func sceneDidLoad() {

    super.sceneDidLoad()

    ObserveForGameControllers()

}   // sceneDidLoad

but that did not work at all.

One last thing:

Here are my Gamepad settings in my Project

It seems I really need some suggestions here.

Appreciate it.