Before iOS 26, you could access a CKShare owner’s identity without any prerequisite by using the Swift code:
let identityNameComponents = ckShare.owner.userIdentity.nameComponents
However, in iOS and macOS 26, Apple restricted this information, introducing the iCloud Extended Share Access entitlement which needs to be set up with the InProcessShareOwnerParticipantInfo value (in an array of strings) before userIdentity returns anything other than nil.

This is a quick one for my first post in a few years, but something that came up with a recent feedback report from Fox and I hadn’t seen mentioned. Hope this is useful for anyone in the same boat!