如何在iOS谷歌地图应用程序上定义闭合多边形？

import GoogleMaps

class ViewController: UIViewController {
    var mapView: GMSMapView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建地图视图
        let camera = GMSCameraPosition.camera(withLatitude: 37.7749, longitude: -122.4194, zoom: 12.0)
        mapView = GMSMapView.map(withFrame: view.bounds, camera: camera)
        view.addSubview(mapView)
        
        // 添加多边形
        let path = GMSMutablePath()
        path.add(CLLocationCoordinate2D(latitude: 37.785834, longitude: -122.406417))
        path.add(CLLocationCoordinate2D(latitude: 37.758859, longitude: -122.404058))
        path.add(CLLocationCoordinate2D(latitude: 37.766845, longitude: -122.451599))
        path.add(CLLocationCoordinate2D(latitude: 37.789988, longitude: -122.467654))
        path.add(CLLocationCoordinate2D(latitude: 37.785834, longitude: -122.406417))
        
        let polygon = GMSPolygon(path: path)
        polygon.fillColor = UIColor(red: 0.25, green: 0, blue: 0, alpha: 0.2)
        polygon.strokeColor = .black
        polygon.strokeWidth = 2
        polygon.map = mapView
    }
}