c# - Uniquely identifying contacts in a Windows Phone Address Book -

consider following situation:

• i save data random contact x address book iso storage
• i leave application , modify contact x in address book
• coming application, how can identify contact x iso storage same contact x modified in address book?

my intention periodically copy user's address book data iso storage , sync server. i'm doing read operations, permitted, if given authorization.

the problem contact id private field, , cannot use contact stores (which have public ids).

also, wp contacts don't have content rules, meaning can have contact no name, 10 phone numbers, no phone numbers, etc, taking piece of content unique identifier not work since consistency not guaranteed.

hash codes not work since modified object results in modified has code.

any appreciated.

found answer - related question posted here.

i decompiled microsoft.phone dll , seems contact.gethashcode returns contact.id value. behavior has been confirmed work expected on various devices , on emulator.

all people consistently insist developers should not allowed access information such contact id - please bear in mind users contact access permission can denied in marketplace. when i'm developing, i'm assuming user understands he's getting himself into, since take time , write meaningful description , ms acceptance testing. if user realities app "breaks privacy" it's not problem developer.

the last paragraph motivated fact saw couple of answers formulated "devs don't need these features, break privacy".