标记已加载到地图上，但折线未显示在谷歌地图上，代码中没有错误

Question

I wrote the code according to documentation for polylines and i am not getting any error in code or no exception is thrown by code. even the app is running fine but polylines which should show up is not loading on map in my android app.

foreach (var route in routeList)
                {
                    if (route.RouteSegmentPoints != null)
                    {

                        Polyline polyline;
                        int color = Android.Graphics.Color.Black;
                        PolylineOptions poly = 
Utils.GetPolyLineOptions(color, 100, true, 100);
                        polyline = _map.AddPolyline(poly);
                        for (int i=0;i<route.RouteSegmentPoints.Count;i++)
                        {
                            point = new 
LatLng(Convert.ToDouble(route.RouteSegmentPoints[i].Latitude), 
Convert.ToDouble(route.RouteSegmentPoints[i].Longitude));
                            //endPoint = new 
LatLng(Convert.ToDouble(route.RouteSegmentPoints[i+1].Latitude), 
Convert.ToDouble(route.RouteSegmentPoints[i+1].Longitude));
                            poly.Add(point);
                        }



                        //System.Console.WriteLine("single Route");
                    }
                }

If anyone knows about solution please let me know thanks in advance.

Answer 1

You should be assigning values to poly before adding it to the _map , so the values you add to it aren't passed in.

foreach (var route in routeList)
{
    if (route.RouteSegmentPoints != null)
    {
        Polyline polyline;
        int color = Android.Graphics.Color.Black;
        PolylineOptions poly = Utils.GetPolyLineOptions(color, 100, true, 100);
        for (int i=0;i<route.RouteSegmentPoints.Count;i++)
        {
            point = new 
LatLng(Convert.ToDouble(route.RouteSegmentPoints[i].Latitude), 
Convert.ToDouble(route.RouteSegmentPoints[i].Longitude));
            poly.Add(point);
        }
        polyline = _map.AddPolyline(poly);
    }
}

If that doesn't work either, you could try wrapping the last line from my code to Run On the Ui Thread because depending on the thread this code is being executed on it may not be updating the UI:

Activity.RunOnUiThread(() => {
    polyline = _map.AddPolyline(poly);
});