如何检查 Flutter 应用程序是否在前台? [英] How do I check if the Flutter application is in the foreground or not?

问题描述

我不想在应用程序处于前台时显示通知.如何查看应用的实时状态?

I don't want to show notification when the app is in foreground. How can I check live state of my app?

推荐答案

在你的 State<...> 类中你需要实现 WidgetsBindingObserver 接口并监听小部件状态变化.像这样:

In your State<...> class you need to implement WidgetsBindingObserver interface and listen for widget state changes. Something like this:

class _MyHomePageState extends State<MyHomePage> with WidgetsBindingObserver {
  AppLifecycleState _notification; 
  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    setState(() {
      _notification = state;
    });
  }

  @override
  initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    ...
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }
}

然后当您想知道状态是什么时，请检查 _notification.index 属性._notification == null => 没有发生状态变化，0 - 恢复，1 - 不活动，2 - 暂停.

Then when you want to know what is the state, check _notification.index property. _notification == null => no state changes happened, 0 - resumed, 1 - inactive, 2 - paused.

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