Friendly reminder: the magic words for dealing with the police are "I do not consent to a search. Am I free to leave?" It's just business: you never need a reason to ask for more money in a negotiation and you never need a reason to avoid waiving your Constitutional rights.

If they need your iPhone address book they can get a search warrant. (Our historical understand is that they do need a reason for asking for that sort of thing, and that your papers and effects enjoy a strong presumption of privacy.)