SwiftUI:如何在MapKit中自定义地理区域的位置？

@State private var region = MKCoordinateRegion(center: CLLocationCoordinate2D(latitude: 37.331516, longitude: -122.030028), span: MKCoordinateSpan(latitudeDelta: 0.2, longitudeDelta: 0.2))

var body: some View {
    Map(coordinateRegion: $region)
}

let coordinates = [
    CLLocationCoordinate2D(latitude: 37.332004, longitude: -122.032151),
    CLLocationCoordinate2D(latitude: 37.331586, longitude: -122.031882),
    CLLocationCoordinate2D(latitude: 37.331586, longitude: -122.029781),
    CLLocationCoordinate2D(latitude: 37.332004, longitude: -122.029512)
]

let polygon = MKPolygon(coordinates: coordinates, count: coordinates.count)

func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
    if let polygon = overlay as? MKPolygon {
        let renderer = MKPolygonRenderer(polygon: polygon)
        renderer.fillColor = UIColor.red.withAlphaComponent(0.5)
        renderer.strokeColor = UIColor.blue
        renderer.lineWidth = 2
        return renderer
    }
    return MKOverlayRenderer(overlay: overlay)
}

Map(coordinateRegion: $region, overlays: [polygon])
    .onAppear {
        mapView.addOverlay(polygon)
    }