I'm deliberating on whether to use CloudKit for an app that requires sharing data amongst self-created groups of users (for e.g. sharing company-wide directories). I would use a public database for this, but I had a couple of questions:- if I create a subscription to listen to record changes for a partcular record type, will all the users get a notification when data changes, or only the logged-in iCloud user amongst his/her multiple devices? can there by 'group' notifications that cross iCloud users?- if there's no way for a 'group' of users to get notifications, I guess polling from the app to CloudKit would work, with the groupID part of the predicate? Or is there another options?Thanks.

Hi,I saw the WWDC talk on the new Contacts framework, and I had a couple of questions about the identifier property:When users upgrade from iOS8 to iOS9, will their old AddressBook recordIDs still work if we are using the AddressBook framework in the app (i.e. haven't upgraded to using Contacts framework)?Are the new CNContact identifiers consistent across iOS and Mac devices? i.e. if we have the identifier on one device, we can lookup the contact on another device with the same identifier?Can these identifiers change in the lifetime of that contact? This was a problem with AddressBook recordIDs ... if you removed the account and then synced it back again, all the contacts would get a different identifier. Same with restoring the device. Will the CNGroup and CNContainer identifiers also be consistent across devices?Hope someone in the Apple Contacts frameworks team can answer. Thanks.