override func viewDidLoad() {
    super.viewDidLoad()

    NotificationCenter.default().addObserver(self, selector: #selector(self.downloadAudioVisualItem), name: NSNotification.Name.AVPlayerItemNewAccessLogEntry, object: nil)
}

func downloadAudioVisualItem() {
    print("Hello")
}

override func viewDidDisappear(_ animated: Bool) {
    super.viewDidDisappear(false)

    NotificationCenter.default().removeObserver(self)
}