struct ContentView: View {
   @State private var appData = ApplicationData.shared

   var body: some View {
      Map(position: $appData.cameraPos) {
         if let route = appData.route {
            MapPolyline(route)
               .stroke(.red, lineWidth: 5)
         }
      }.onAppear {
         appData.calculateRoute()
      }
   }
}