将上下文传递给 showdialog 以便在起始页加载时不会丢失

如何解决将上下文传递给 showdialog 以便在起始页加载时不会丢失

我试图在启动应用程序时显示信息对话框。

关闭后，会出现另一个请求许可的窗口。我在 initState 函数中调用它。它有效，但我注意到第一个信息对话框也会在 15 秒过去后自行关闭。据我了解，这是因为应用程序已加载且上下文丢失。

当我将 runApp(MyApp()) 更改为 runApp(MaterialApp(home: MyApp())) 时。它有效，弹出窗口不会消失。但是其他页面上的其他显示对话框没有自动关闭 (Navigator.of(context).pop() 并且 Navigator.pop(context) 不起作用。

如何正确地将上下文传递给我的初始显示对话框，以便在开始页面加载时它不会消失？

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(MyApp());
}
class MyApp extends StatefulWidget {
  static final navKey = new GlobalKey<NavigatorState>();
  const MyApp({Key navKey}) : super(key: navKey);

  @override
  _MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
@override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) async {
      final context = MyApp.navKey.currentState.overlay.context;
       await showDialogIfFirstLoaded(context);
       await initPlatformState();
    });
  }
showDialogIfFirstLoaded(BuildContext context,prefs) async {
    bool isFirstLoaded = prefs.getBool(keyIsFirstLoaded);
    if (isFirstLoaded == null) {
      return showDialog(
        context: context,builder: (BuildContext context) {
          // return object of type Dialog
           return new AlertDialog(
                 // title: new Text("title"),content: new Text("//"),actions: <Widget>[
                  new FlatButton(
                    child: new Text(".."),onPressed: () {
                  Navigator.of(context).pop();
                },),],);
        },);
    }
  }
@override
  Widget build(BuildContext context) {
    return MaterialApp(    
      navigatorKey:MyApp.navKey,home: new SplashScreen(),}
class SplashScreen extends StatefulWidget {
  @override
  _SplashScreenState createState() => new _SplashScreenState();
}

class _SplashScreenState extends State<SplashScreen> with SingleTickerProviderStateMixin {
  Timer _timer;
  bool _visible = true;
  startTime() async {  
      _timer = Timer(new Duration(seconds: 5),navigationPage); 
  }
  void navigationPage() {
    Navigator.of(context).pushReplacementNamed('/home');
  }
  @override
  void initState() {
    _timer = Timer(Duration(seconds: 4),() => setState(
            () {
          _visible = !_visible;
        },);
    startTime();
    super.initState();
  }
  @override
  void dispose() {
    _timer.cancel();
    super.dispose();
  }
  @override
  Widget build(BuildContext context) {
    return new Stack(
      children: <Widget>[
        Container(
          width: double.infinity,child: Image.asset('images/bg.jpg',fit: BoxFit.cover,height: 1200,Container(
          width: double.infinity,color: Color.fromRGBO(0,0.8),Container(
          alignment: Alignment.center,child: Row(
            children: <Widget>[
              Expanded(
                flex: 2,child: Container(
                  child: Text(''),);
  }
}