I haven't tried this, but something like this should work - the AddressDictionary used by MKPlacemark
is the same format as used by AddressBook
NSMutableDictionary a = new NSMutableDictionary();
a.Add(ABPersonAddressKey.City, new NSString(city));
a.Add(ABPersonAddressKey.State, new NSString(state));
a.Add(ABPersonAddressKey.Zip, new NSString(zip));
a.Add(ABPersonAddressKey.Street, new NSString(addr1));