Is that above snippet worked for you ? For me the clientDataJSON was received empty on 'didCompleteWithAuthorization' after the registration. I just gone with the same flow as you mentioned.
Sathish95
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution