Swift5.0 监听键盘高度变化

1.注册监听事件 

NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillChangeFrame(node:)), name: UIResponder.keyboardWillChangeFrameNotification, object: nil)

2.执行事件

@objc func keyboardWillChangeFrame(node : Notification){
        
        print(node.userInfo ?? "")
        // 1.获取动画执行的时间
        let duration = node.userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey] as! TimeInterval
        
        // 2.获取键盘最终 Y值
        let endFrame = (node.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as! NSValue).cgRectValue
        let y = endFrame.origin.y
        
        //3计算工具栏距离底部的间距
        let margin = UIScreen.main.bounds.height - y
        print("键盘高度",margin)
        
        //4.执行动画
        webView_bottom.constant = margin
        UIView.animate(withDuration: duration) {
            self.view.layoutIfNeeded()
        }
    }

3.移除监听

deinit {
        NotificationCenter.default.removeObserver(self)
    }