Hi,
Yes you are doing correctly. UserCollection is an ArrayCollection , so you also do userCollection.getItemAt(i) as UserDescriptor to get the ith value.
UserCollection has all the user descriptors. If you want to loop over just the hosts/participants/viewer , you can also use the respective collection ie. HostCollection, ParticipantCollection or AudienceCollection respectively.
All these collections are in UserManager.
Thanks
Hironmay Basu