We created our own GiftCode system for In-App-Purchase
I cannot reveal the (technical) details.
For app developers, promocodes are a wonderful thing for 1) customer service, 2) media outreach, 3) reaching out to app reviewers. Its painful when you switch from selling standalone app to In-App-Purchase, because Apple doesn't have promocodes. But we couldn't do without it, so we built it into the app.
Is it against Apple's Terms&Conditions? I don't know. Regardless, its #HackerPride!
I think this is interesting, but are you promoting this or just announcing what you've accomplished? I would like to know a bit more about it.
I am not able to promote this, I wish I could. But I came to know from another friend that they tried to do a promocode within their IAP app, and they got rejected by Apple. So mum's the word.
On the other hand, we'll do the same for Android app as well. Because Android has no promocodes and that suck! I hope once thats done, we'll be able to make it public.