Not getting call back!

[iOS]. How to get call back when user click on right bar button in SBUGroupChannelListViewController.
I want to launch my own view controller when user click on plus button in SBUGroupChannelListViewController.

I need it for iOS SDK. I gone through the Documentation i tried below code but no luck. Can some one please help me on this?

    let mainVC = SBUGroupChannelListViewController()
    mainVC.headerComponent?.delegate = self
    let naviVC = UINavigationController(rootViewController: mainVC)
    naviVC.modalPresentationStyle = .fullScreen
    present(naviVC, animated: true)