标记当前位置时,坐标始终为0,0

我正在使用谷歌地图服务制作一个使用Xcode 9.2和Swift 4的应用程序。当我按下按钮时,我希望在地图视图上用一个标记标记我的当前位置。相反,当点击按钮时,它会将我带到坐标0,0。我做错了什么?提前感谢您的帮助。

//Location Manager

var userLocation = CLLocation()

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {

userLocation = locations.last!

let camera = GMSCameraPosition.camera(withLatitude: userLocation.coordinate.latitude, longitude: userLocation.coordinate.longitude, zoom: 14);
self.googleMapsView.camera = camera

//Finally stop updating location otherwise it will come again and again in this delegate

self.locationManager.stopUpdatingLocation()

}

//Button Marker Function

@IBAction func markCurrentLocation(_ sender: UIButton) {

let center = CLLocationCoordinate2D(latitude: userLocation.coordinate.latitude, longitude: userLocation.coordinate.longitude)

    let camera = GMSCameraPosition.camera(withLatitude: userLocation.coordinate.latitude, longitude: userLocation.coordinate.longitude, zoom: 14);
    self.googleMapsView.camera = camera
    self.googleMapsView.isMyLocationEnabled = true

    let marker = GMSMarker(position: center)

    print("Latitude :- \(userLocation.coordinate.latitude)")
    print("Longitude :-\(userLocation.coordinate.longitude)")

    marker.map = self.googleMapsView

    marker.title = "Current Location"

    googleMapsView.animate(to: camera)

    //Finally stop updating location otherwise it will come again and again in this delegate

    self.locationManager.stopUpdatingLocation()
}