Iphone: Is it allowed to make the user register seperatly from app store?

Ive tried to contact Apple about this, but they refuse to give me any answers. Do any of you know if it`s allowed to make the user register with a username,password and phone number before they can use the the application they have already开发者_StackOverflow中文版 downloaded from app store?

Thanks!

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Well, I've seen several applications that make you at least register with a username, password, and email address. I believe it's safe to say that requiring this is OK with Apple.