Information about user

What information about user can I get? And how? I need to get iOS device ID (but I believe Apple doesn't want me to do that anymore?) as well as probably Apple ID (iTunes Store ID) of the use开发者_如何学运维r? My concern is to identify the user. Say, I have my app, and user purchased it from his iPhone, but then he is on his iPad, and I want to identify him properly. How can I do that? Anything I can get out?

You should have the user create a username within your app. Your app is guaranteed to be rejected if you request the user's Apple ID, and I know from experience that unless you have a really good reason to be asking for the user's name, Apple generally frowns upon this as well. So, as I said, either collect a username, or maybe you could even get by with a user's email. Good luck!