Possible Duplicate:
How does Square's CardCase App Do This?
Is this forbidden? Square's iPhone App CardCase seems to be doing this when you create an account. It prefills fields with your email address, photo, and name from the iPhone's address book.
If not forbidden, how does one accomplish it?
Edit: I suspect they are doing this:
Programmatically get own phone number in iOS
and then looking for the phone number in the address book.
Getting Address Book information is not prohibited, in fact, there is a framework dedicated to the Address Book. See ABAddressBook Class Reference. Also, there are a ton of examples on the net that demonstrate how to access the address book, getting entries as well as adding entries.
There are several questionable methods for obtaining the current user's name or email which you could then use to look up their full contact details. However, these run you the risk of getting rejected by Apple. Instead, I would recommend asking for something simple (like phone number) to start off with and using that entered information to try to helpfully autofill the rest. Or assuming you are creating accounts for the user you could use Facebook, Twitter, Google and/or some other 3rd party authentication system instead of requiring all of their details again for your specific app.
