谷歌地图myLocationButton在标签栏控制器Swift 3下

import GoogleMaps

class MapViewController: UIViewController {
    var mapView: GMSMapView!

    override func viewDidLoad() {
        super.viewDidLoad()

        let camera = GMSCameraPosition.camera(withLatitude: 37.7749, longitude: -122.4194, zoom: 12.0)
        mapView = GMSMapView.map(withFrame: view.bounds, camera: camera)
        view.addSubview(mapView)
    }
}

override func viewDidLoad() {
    super.viewDidLoad()

    let camera = GMSCameraPosition.camera(withLatitude: 37.7749, longitude: -122.4194, zoom: 12.0)
    mapView = GMSMapView.map(withFrame: view.bounds, camera: camera)
    mapView.isMyLocationEnabled = true
    mapView.settings.myLocationButton = true
    view.addSubview(mapView)
}