let scrollView = UIScrollView()

let keyboardManager = RKKeyboardManager()
// or let keyboardManager = RKKeyboardManager(scrollView: scrollView)

// keyboardManager.subscribe()
// keyboardManager.unsubscribe()

func setupKeyboardManager() {
    keyboardManager.setOnWillChangeFrameBlock { [weak self] keyboardFrame, keyboardEvent in
        guard let sself = self else { return }
        switch keyboardEvent {
        case .willShow, .justChange:
            // do ...
        case .willHide:
            // do ...
        }
    }
}