动画用户位置圈swift 3+ Google地图

import GoogleMaps

class ViewController: 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: CGRect.zero, camera: camera)
        view = mapView
    }
}

let marker = GMSMarker()
marker.position = CLLocationCoordinate2D(latitude: 37.7749, longitude: -122.4194)
marker.map = mapView

let circle = GMSCircle(position: CLLocationCoordinate2D(latitude: 37.7749, longitude: -122.4194), radius: 100)
circle.fillColor = UIColor(red: 0, green: 0.7, blue: 0, alpha: 0.1)
circle.strokeColor = UIColor.green
circle.strokeWidth = 1
circle.map = mapView