如何从mapkit注解导航- SwiftUI/Xcode 11

import SwiftUI
import MapKit

struct ContentView: View {
    @State private var region = MKCoordinateRegion(center: CLLocationCoordinate2D(latitude: 37.331516, longitude: -122.030028), span: MKCoordinateSpan(latitudeDelta: 0.2, longitudeDelta: 0.2))
    @State private var annotationCoordinate = CLLocationCoordinate2D(latitude: 37.331516, longitude: -122.030028)
    
    var body: some View {
        VStack {
            Map(coordinateRegion: $region, annotationItems: [annotationCoordinate]) { coordinate in
                MapAnnotation(coordinate: coordinate) {
                    Image(systemName: "mappin")
                        .foregroundColor(.red)
                        .onTapGesture {
                            startNavigation()
                        }
                }
            }
        }
    }
    
    func startNavigation() {
        let destination = MKMapItem(placemark: MKPlacemark(coordinate: annotationCoordinate))
        destination.name = "Destination"
        
        MKMapItem.openMaps(with: [destination], launchOptions: [MKLaunchOptionsDirectionsModeKey: MKLaunchOptionsDirectionsModeDriving])
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}