Migrating VBA Script to .Net

Question

Ok,

This is my last attempt at this, I have been trying for the last day to move one script from 9.3.1 to 10.

I have a small Function that runs within a larger VBA script, so far from what I can tell, it falls down in this section when I have converted it to VB.Net:

Private Function GetLayer(sLayer) As ILayer

Dim pMxDoc As IMxDocument
  Dim i As Integer
  Dim players As IEnumLayer
  Dim pLayer As ILayer
  Dim pL As ILayer
  Dim ii As Integer
  Dim pCL As ICompositeLayer
  Dim pApp As IApplication
  Set pApp = New AppRef
  
  On Error GoTo GetLayer_Err <---- It doesnt pass this point...

If TypeOf pApp.Document Is IMxDocument Then
  
    Set pMxDoc = pApp.Document
    Set players = pMxDoc.FocusMap.layers(, True)
    
  End If
....

It does not pass -

pApp = New AppRef

It will also not allow me to use the IApplication due to a "friend" error.
Please could someone help me understand why this is the case?

I am still very new to scripting and have been relying on online samples and help to get me here. From what I can tell this is the last hurdle.

I am using Visual Studio Express 2008
Vb.Net and creating an ArcMap 10 Add-In.

Any and all comments / help will be greatly appreciated.

Thank you!!

RuchiraWelikala · Answer

The OnCreate Sub is right above the OnClick sub (or should be). They are autogenerated in VB.NET when you create the application.  
I've never used the "My.MyMap..." method before for getting the Document or the application from ArcMap.  That's one of the key differences between VBA and .NET.  VBA used ThisDocument while .NET uses m_application.

KeaganAllan · Answer

Ok,

So in my main module (where Public Overides xyz On_Click) is, I should have added the "Hook" phrases?

In the end what I put forward has worked, I am not sure why though.

Thanks for your responses, I am still learning and your patience is greatly appreciated.

RuchiraWelikala · Answer

When you create a command through VB.NET, it sets up the hook for the application automatically.
Looks like this at the beginning of your code:
NOTE:  This is autogenerated code! Should already exist in your base command!
    Public Overrides Sub OnCreate(ByVal hook As Object)
        If Not hook Is Nothing Then
            m_application = CType(hook, IApplication)

'Disable if it is not ArcMap
            If TypeOf hook Is IMxApplication Then
                MyBase.m_enabled = True
            Else
                MyBase.m_enabled = False
            End If
        End If
        ' TODO:  Add other initialization code
    End Sub

So your code should look something like this:Public Function GetLayer(ByVal sLayer) As ILayer

Dim pMxDoc As IMxDocument
Dim i As Integer
Dim players As IEnumLayer
Dim pLayer As ILayer
Dim pL As ILayer
Dim ii As Integer
Dim pCL As ICompositeLayer

pMxDoc = m_application.Document
On Error GoTo GetLayer_Err

players = pMxDoc.FocusMap.Layers(, True)

End If

pLayer = players.Next
Do While Not pLayer Is Nothing
If TypeOf pLayer Is ICompositeLayer Then
pCL = pLayer
For ii = 0 To pCL.Count - 1
pL = pCL.Layer(ii)
If UCase(pL.Name) = UCase(sLayer) Then
GetLayer = pL
Exit Function
End If
Next
Else
If UCase(pLayer.Name) = UCase(sLayer) Then
GetLayer = pLayer
Exit Function
End If
End If
pLayer = players.Next
Loop

Exit Function

GetLayer_Err:

End Function

Should work.