Getting all registered user list using XMPPFramework for iOS

Hi,
I am using jabbered for the development of a chat application for iOS. I have successfully set up the server and my code is also working fine. I want to fetch all the registered users to show in the app but I am not getting it with a user account. If I use the jabber ID used for admin purpose, it returns all the users. What should I do to get all the users with the user id.

Thanks