I imagine how to do this. There are some experiments in attached file.
A documentation talks about "notifications".
To handle the notifications, you need to set the observers. Of course, not all, but needed only. For example, you want to monitor 'selections'.
	
	
	
	
	
	
	
	
	
		    [[NSNotificationCenter defaultCenter] addObserver: self selector: @selector (_pdfviewselectionchangednotification)    name: PDFViewSelectionChangedNotification    object: nil];
	 
	
	
		
	
 
Then you can process in B4i subroutine. Example
	
	
	
	
	
	
	
	
	
		Private Sub PDFViewSelectionChangedNotification ' A notification posted when the current selection has changed.
   
    Dim nativeObjectCurrentSelection                                   As NativeObject
   
    nativeObjectCurrentSelection = nativeObjectPDFView.GetField ("currentSelection")
    If nativeObjectCurrentSelection.IsInitialized Then
        Log ("PDFViewSelectionChangedNotification: Current Selection = " & nativeObjectCurrentSelection.GetField ("string").AsString)
    Else
        Log ("PDFViewSelectionChangedNotification: Not selected")
    End If
                 
End Sub