NotificationCenter
            .default
            .rx
            .notification(UIResponder.keyboardWillShowNotification)
            .subscribe {notification in
                let frameEndUserInfoKey = UIResponder.keyboardFrameEndUserInfoKey
                if let info = notification.element?.userInfo {
                    if let kbFrame = info[frameEndUserInfoKey] as? CGRect {
                        
                        let distance = self.window!.height - self.y - self.height
                        if distance < kbFrame.height + 20 {
                            
                            self.snp.remakeConstraints { make in
                                make.width.equalTo(311.uiX)
                                make.centerY.equalToSuperview().offset(self.window!.height - kbFrame.height - 20 - self.height/2)
                            }
                        }
                        
                    }
                }
            }.disposed(by: rx.disposeBag)
        
        NotificationCenter
            .default
            .rx
            .notification(UIResponder.keyboardWillHideNotification)
            .subscribe {notification in
                self.snp.remakeConstraints { make in
                    make.width.equalTo(311.uiX)
                    make.centerY.equalToSuperview()
                }
            }.disposed(by: rx.disposeBag)