Question

我对Flutter Bloc真的很陌生，并且在Bloc实现方面遇到了一些问题，我试图在启动屏幕小部件中的状态更改后进行导航。

状态更新为 InitSuccess 后，它应该导航到 LoginScreen ，但是这种导航会发生很多次。

在状态更改为 InitSuccess 之后，我无法理解该怎么办，在此之后，该团体保持活动并调用了很多次 LoginScreen 。

启动画面

implementation fileTree(include: ['*.jar'], dir: 'libs')
implementation 'com.android.support:appcompat-v7:26.1.0'
implementation 'com.google.android.gms:play-services-ads:17.1.3'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.1'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
implementation 'org.jsoup:jsoup:1.10.3'
implementation 'com.google.firebase:firebase-core:16.0.1'
implementation'com.google.firebase:firebase-config:16.1.0'

Splash Bloc

class SplashScreen extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => _SplashScreenState();
}

class _SplashScreenState extends State<SplashScreen> {
  SplashBloc _splashBloc;
  final _scaffoldKey = GlobalKey<ScaffoldState>();

  @override
  void initState() {
    _init();
    super.initState();
  }

  @override
  void dispose() {
    _splashBloc.dispose();
    super.dispose();
  }

  void _init() {
    Future.delayed(Duration.zero, () {
      checkDeviceConnection(context);
      BlocSupervisor().delegate = SplashBlocDelegate();
      final bool isIOS = Theme.of(context).platform == TargetPlatform.iOS;
      _splashBloc = SplashBloc(
        firebaseService: FirebaseService(context),
        authService: AuthService(context),
        devicesService: DevicesService(context),
      );
      _splashBloc.dispatch(SplashInitEvent(isIOS: isIOS));
    });

@override
  Widget build(BuildContext context) {
    SystemChrome.setEnabledSystemUIOverlays([]);
    return BlocBuilder<SplashEvent, SplashState>(
      bloc: _splashBloc,
      builder: (
        BuildContext context,
        SplashState state,
      ) {
        if (state is InitFailure) {
          Future.delayed(Duration.zero, () {
            showWarningSnackBar(_scaffoldKey, state.error);
          });
        }

        if (state is InitSuccess) {
          Future.delayed(Duration.zero, () {
            Navigator.push(
              context,
              MaterialPageRoute(
                builder: (context) => LoginScreen(),
              ),
            );
          });
        }

        return Scaffold(
          key: _scaffoldKey,
          body: Container(
            decoration: appScreenGradient,
            alignment: Alignment.center,
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                Image.asset(
                  "assets/images/splash_screen/logo_splash.png",
                  width: 172.88,
                  height: 144.55,
                  fit: BoxFit.contain,
                ),
                SizedBox(
                  height: 20.0,
                ),
                LoadingSpinner(
                  spinnerColor: Theme.of(context).primaryColorLight,
                ),
              ],
            ),
          ),
        );
      },
    );
  }

Answer 1

我找到了以下解决方案：

if (state is LoggedIn) {
  WidgetsBinding.instance.addPostFrameCallback((_) { 
    // Navigation
  });
}

我用这个addPostFrame回调包装了导航，以延迟其外观。

关于状态更改的集团导航

1 个答案: