My friend has the name Oisin which is a male Australian name. How exactly does one pronounce it?

Because he was a friend I met online, I never had the opportunity to say it out loud, but my brain always mentally pronounced it as "Oyzun" like what one would find in the word "boysenberry". Years later when I did say it out loud to a native Aussie, he laughed and laughed, informing me that I was saying it wrong, however, refused to tell me the right way, as he wanted to leave me stranded in a world that would mock my pronunciation. Now, my twin sister, who is in Australia, tells me that she asked a native to confirm officially how one says it, and alas, this friend uttered it just as I had said originally! "Oyzun"! Unfortunately, however, he had never heard of the name. I'm more confused than ever before on this issue, and if someone (particularly if you are named Oisin) could give a definitive answer as to how to say it, I would be most appreciative! Time to kick back with some hot chips in my thongs now. My friend bought them for me (the chips, not the thongs) as I was the only one to help him remove a shuttle wedged in his ear after a rough game of badminton. Bonzer moment!