How to Obtain INALayer from ILayer?

Question

I have ILayer, how do i obtain INALayer,

if (TypeOf layer Is INALayer) is false?

I am using ArcGIS 9.3.1

Answer 1

Part of This sample, among other things, shows how to get a reference to the INALayer. Basically, it goes like this:

// app is an IApplication reference
ESRI.ArcGIS.NetworkAnalystUI.INetworkAnalystExtension naExt = 
    (ESRI.ArcGIS.NetworkAnalystUI.INetworkAnalystExtension)
    app.FindExtensionByName("Network Analyst");
ESRI.ArcGIS.NetworkAnalystUI.INAWindow naWindow = naExt.NAWindow;
if (naWindow.ActiveAnalysis == null || naWindow.ActiveCategory == null)
{
    System.Windows.Forms.MessageBox.Show(
        "There must be an active analysis layer and an active category");
    return ;
}
ESRI.ArcGIS.NetworkAnalyst.INALayer naLayer = naWindow.ActiveAnalysis;