Append text in NSTextView while not breaking Undo Stack

Question

I have an NSTextView based application where I have various commands changing the text. In order to replace a portion I use the following snippet:

if ([textView shouldChangeTextInRange:range replacementString:string]) { //string
  [textStorage beginEditing];
  [textStorage replaceCharactersInRange:range withAttributedString:attributedString];
  [textStorage endEditing];
  [textView didChangeText];
}

My issue starts when I want to append at the end of the textview. In that case I cannot use shouldChangeTextInRange:range replacementString:string so I use :

textView.textStorage?.beginEditing()
self.textView.textStorage?.append(NSAttributedString(string: string))
self.textView.scrollToEndOfDocument(nil)
textView.textStorage?.endEditing()
textView.didChangeText()

While it works fine for attributes, Undo totally breaks. Any idea how I can fix that issue?