用于重新拉起"广告页"

 main.dart 应用启动文件 

void main()async {

runApp(

MyApp(),

);

}

构建 初始页面my_app.dart

class MyApp extends StatefulWidget {

  @override

  _MyAppState createState() => _MyAppState();

}

class _MyAppState extends State with WidgetsBindingObserver {

  @override

  void initState() {

    super.initState();

  //添加拉起广告

   // AdManager.showAd(state, _context);  //不适合在此添加

  }

   @override

  Widget build(BuildContext context) {

    return MaterialApp(

debugShowCheckedModeBanner:false,

initialRoute:"tabs",   //导航页面

 onGenerateRoute:Routes.onGenerateRoute,

navigatorKey:Routes.navigatorKey,

);

  }

}

初始导航页面设置tabs.dart 

class Tabs extends StatefulWidget {

  @override

  _TabsState createState() => _TabsState();

}

class _TabsState extends State with WidgetsBindingObserver {

  int _currentIndex = 0;

//HomePage 首页，HistoryPage历史记录页，GuidePage教程页，MinePage个人中心页

  final pages = [HomePage(), HistoryPage(), GuidePage(), MinePage()];

@override

  void dispose() {

    // TODO: implement dispose

    WidgetsBinding.instance.removeObserver(this);

    super.dispose();

  }

  @override

  void didChangeAppLifecycleState(AppLifecycleState state) {

    super.didChangeAppLifecycleState(state);

    //在此添加拉起"广告页"或"功能页"

    AdManager.showAd(state, _context);

  }

}