Должно работать следующее:
ABAddressBookRef aB = ABAddressBookCreate();
ABRecordRef source = ABAddressBookCopyDefaultSource(aB); // or get the source with ABPersonCopySource(somePersonsABRecordRef);
NSArray *arr = (NSArray *)ABAddressBookCopyArrayOfAllPeopleInSourceWithSortOrdering(aB, source, kABPersonSortByLastName);
// you can also use kABPersonSortByFirstName instead of kABPersonSortByLastName