MapTableViewController.swift

locationManager = CLLocationManager()

if CLLocationManager.authorizationStatus() == .notDetermined {
    locationManager.requestAlwaysAuthorization()
}
    // 2. 用戶不同意
else if CLLocationManager.authorizationStatus() == .denied {
    DispatchQueue.main.async(){
        let alertController = UIAlertController(title: "定位權限已關閉", message: "如要變更權限，請至 設定 > 隱私權 > 定位服務 開啟", preferredStyle: .alert)
        let okAction = UIAlertAction(title: "ok", style: .default, handler: nil)
        alertController.addAction(okAction)
        self.present(alertController, animated: true, completion: nil)
    }//DispatchQueue
}
    // 3. 用戶已經同意
else if CLLocationManager.authorizationStatus() == .authorizedAlways {
    locationManager.startUpdatingLocation()
}


let longPress = UILongPressGestureRecognizer(target: self, action: #selector(MapTableViewController.mapLongPress(_:))) // colon needs to pass through info
longPress.minimumPressDuration = 1.0 // in seconds
mapView.addGestureRecognizer(longPress)