Getting GraphicsLayer Dynamicaly

[jonataspovoas]

Hi,

I'm making a "clear graphics" function for my application, and i need to clear my 3 GraphicsLayers.

I tried this:

        private void btnLimparGraficos_click(object sender, RoutedEventArgs e)
        {
            foreach (ESRI.ArcGIS.Client.GraphicsLayer layer in Mapa.Layers)
            {
                layer.ClearGraphics();
            }
        }

This code has thrown this exception:

throw new Error("Unhandled Error in Silverlight Application Unable to cast object of type 'ESRI.ArcGIS.Client.ArcGISDynamicMapServiceLayer' to type 'ESRI.ArcGIS.Client.GraphicsLayer'.   
    em MDSalvador.MainPage.btnLimparGraficos_click(Object sender, RoutedEventArgs e)
    em System.Windows.Controls.Primitives.ButtonBase.OnClick()
    em System.Windows.Controls.Button.OnClick()
    em System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(MouseButtonEventArgs e)
    em System.Windows.Controls.Control.OnMouseLeftButtonUp(Control ctrl, EventArgs e)
    em MS.Internal.JoltHelper.FireEvent(IntPtr unmanagedObj, IntPtr unmanagedObjArgs, Int32 argsTypeIndex, String eventName)");

This is my map:

   <esri:Map x:Name="Mapa" Background="#FFC3D2E5" MouseClick="Mapa_MouseClick" ExtentChanged="Mapa_ExtentChanged" IsLogoVisible="False" Margin="0" Extent="534290.354886005,8558896.08922354,584298.229116458,8591401.20747334">

                    <i:Interaction.Behaviors>
                        <esri:ConstrainExtentBehavior ConstrainedExtent="515281.548717264,8545182.63295419,605292.978740125,8611976.82904258" />
                    </i:Interaction.Behaviors>

                    <esri:ArcGISDynamicMapServiceLayer ID="Mapa Base" ImageFormat="JPG"
      />
                    
                    <esri:ArcGISDynamicMapServiceLayer ID="Ortofoto" ImageFormat="PNG8"
      />

                    <esri:ArcGISDynamicMapServiceLayer ID="Logradouros" ImageFormat="PNG32"
      />

                    <esri:ArcGISDynamicMapServiceLayer ID="Projetos Viários" ImageFormat="PNG32"
      />

                    <esri:ArcGISDynamicMapServiceLayer ID="Bairros" ImageFormat="PNG32"
      />

                    <!-- Utilizado no Desenho no Mapa - Paula Soane - 23/09/2010-->
                    <esri:GraphicsLayer ID="MyGraphicsLayer" />

                    <!-- Utilizado no Zoom por coordenadas - Jonatas Lima Povoas - 07/10/2010-->
                    <esri:GraphicsLayer ID="layerGraficoBuscaCoordenadas">
                    </esri:GraphicsLayer>

                    <!-- Utilizado na Busca de Bairros - Ygor Thomaz - 01/10/2010-->
                    <esri:GraphicsLayer ID="layerGraficosResultadosBairros" >
                    </esri:GraphicsLayer>

                    <!-- Utilizado na Busca de Logradouros - Ygor Thomaz - 20/09/2010-->
                    <esri:GraphicsLayer ID="layerGraficosResultadosLogradouros" >
                    </esri:GraphicsLayer>
                </esri:Map>

So, what's the problem with my code and how can i fix it?

[TerryGiles]

try testing to see if the layer is a GraphicsLayer first -

        public void Button1_Click(object sender, RoutedEventArgs e)
        {
            GraphicsLayer Glayer;

            for (int i = 0; i < MyMap.Layers.Count; i++)
            {
                if (MyMap.Layers is GraphicsLayer)
                {
                    Glayer = MyMap.Layers as GraphicsLayer;
                    Glayer.ClearGraphics();
                }
            }
        }

[jonataspovoas]

try testing to see if the layer is a GraphicsLayer first -

        public void Button1_Click(object sender, RoutedEventArgs e)
        {
            GraphicsLayer Glayer;

            for (int i = 0; i < MyMap.Layers.Count; i++)
            {
                if (MyMap.Layers is GraphicsLayer)
                {
                    Glayer = MyMap.Layers as GraphicsLayer;
                    Glayer.ClearGraphics();
                }
            }
        }

Thanks a lot, it worked! =D