如何将基于类的生命周期方法转换为功能方法？

Question

在以下代码中：

  componentDidMount() {
    registerForPushNotificationsAsync();
    this._notificationSubscription = Notifications.addListener(this._handleNotification);
  }

将Notifications.addListener(this._handleNotification);分配给this._notificationSubscription和简单地进行操作之间有什么区别：

  componentDidMount() {
    registerForPushNotificationsAsync();
    Notifications.addListener(this._handleNotification);
  }

还要如何将其转换为如下所示的功能组件格式？

    useEffect(() => {
        registerForPushNotificationsAsync();
        Notifications.addListener(handleNotification);
    }, []);

Answer 1

useEffect(() => {
        registerForPushNotificationsAsync();
        const subscription =Notifications.addListener(handleNotification);
        return () => {
            // Call method for clear subscription. I asume that it is remove but it can be another
            subscription.remove()
        }
    }, []);