In Inventor, we might have many TitleBlockDefinitions in a drawing under "Drawing Resources". In case you want to replace the TitleBlockDefintion in a sheet with new TitleBlockDefinition, we need to delete the TitleBlockDefinition in the sheet and then add the new TitleBlockDefinition.
Below is a VB.NET code which will delete aTtitleBlockDefinition and add a new one. To try this sample, before you run the code, start Inventor, File->New->Standard.idw (open a new drawing).In this particular drawing, code will delete "ANSI - Large" and then add "ANSI A".
Public Sub DeleteTitleBlockOnSheet()
' Set a reference to the drawing document.
' This assumes a drawing document is active.
Dim oDrawDoc As DrawingDocument
oDrawDoc = m_inventorApplication.ActiveDocument
' Obtain a reference to the desired border defintion.
Dim oTitleBlockDef1 As TitleBlockDefinition
oTitleBlockDef1 = oDrawDoc.TitleBlockDefinitions.Item("ANSI A")
' Val1 will be true because this titleblockdefinition
' is present in the drawing doc
Dim Val1 As Boolean = oTitleBlockDef1.IsReferenced
' Obtain a reference to the desired border defintion.
Dim oTitleBlockDef2 As TitleBlockDefinition
oTitleBlockDef2 = oDrawDoc.TitleBlockDefinitions. _
Item("ANSI - Large")
' Val2 will also be true because this titleblockdefinition
' oTitleBlockDef2 is present in the drawing doc
Dim Val2 As Boolean = oTitleBlockDef2.IsReferenced
Dim oSheet As Sheet = oDrawDoc.ActiveSheet
' Sheet has only ANSI - Large TitleBlockDefinition
' (oTitleBlockDef2) - Check to see if the sheet already
' has a title block and delete it if it does.
If oSheet.TitleBlock.Definition Is oTitleBlockDef1 Then
oSheet.TitleBlock.Delete()
End If
If oSheet.TitleBlock.Definition Is oTitleBlockDef2 Then
oSheet.TitleBlock.Delete()
End If
Dim oTitleBlock As TitleBlock
oTitleBlock = oSheet.AddTitleBlock(oTitleBlockDef1)
End Sub
