we implement in-app purchase, but want to receive some information about user: the user will have an option of preordering some content without payment.so that our servers wouldn’t work useless we’d like to force to register.
Can we make some request and learn the user’s id, which he uses in AppStore.
or it is prohibited?
I don’t have a solid answer for you, and nothing to cite. But I’m almost positive this is not permitted. I’d suggest reading the docs, and doing a bit of research.
You can likely find a way to get the user ID, but it will probably result in the rejection of you app. Apple doesn’t like this kind of behavior.