To answer my own question - Yes, I was missing something ! :-( One of those stupid bugs that you go over being persuaded that there is nothing wrong. I was trying to do a to_string on a pointer to an int without dereferencing it - as I said, stupid. Sorry for the bother.

Ah sorry, I forgot to add the script I mentioned, but, when trying to include it here, it ended up as a mess. I simply used the same python script commands as described in the aforementioned article.

So I searched further and found that, during the process of conversion, I could obtain the spec object spec = model.get_spec(). I then dumped this out to a file and saw specificationVersion: 6. So, is this a bug in the version 5.0b5 of CoreML tools ?

@robnotyou, I am sorry that you felt I was being rude, that was not my intention. I can already create the stamp in swift, that's not a problem - its using it to create a continuous "line" of stamps. @OOPer, my question stated that I am using swift a couple of times and I gave the equivalent code in java to illustrate my need - thought that was sufficient info.