This extension I've done for myself to work with in-app purchases on Apple's App Store since internal GameMaker's implementation doesn't fit some of my needs. So I decided to publish it public - maybe someone will find it useful.
See documentation here: https://docs.google.com/document/d/1ozlf4ZNWm-3BaLhgoHu00Cdj59WpbyhStw8xr8hSmJw/edit?usp=sharing
End User Licence Agreement (EULA).
