颤动流块以显示句柄可见状态

Question

我有一个小部件isLive，它根据 bloc 返回的值更改状态。但是每次我运行应用程序时，我都会得到

在 null 上调用了 getter 'progressStateStream'

我试过关注这个answer

 Widget isLive() {
    return Container(
        child: StreamBuilder<bool>(
      stream: _bloc.progressStateStream,
      builder: (context, snapshot) {

        return Visibility(
          maintainState: true,
          visible: snapshot.data ?? false,
          child: ClipRRect(
            borderRadius: BorderRadius.all(Radius.circular(10)),
            child: Container(
              color: Colors.pink[50],
              height: 50,
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: <Widget>[

                  Text("yaay i'm visible"),

                  RaisedButton(
                    shape: RoundedRectangleBorder(
                        borderRadius: BorderRadius.circular(20)),
                    child: Text(
                      "hide"
                    ),
                    color: Colors.white,
                    onPressed: () {
                      _bloc.changeProgressState(state: false);
                    },
                  )
                ],
              ),
            ),
          ),
        );
      },
    ));
  }

这是我的集团

  //this Subject allows sending data, error and done events to the listener
  final PublishSubject<bool> _progressStateSubject = new PublishSubject();

  //the listener are streaming on changes
  Observable<bool> get progressStateStream => _progressStateSubject.stream;

  //to change your progress state
  void changeProgressState({bool state}) => _progressStateSubject.sink.add(state);

另外，如果我想用 hydrad bloc 保存状态，我会怎么做呢

Answer 1

通过将 bloc 添加到 init 状态来将我的 bloc 初始化为 init 状态来修复它

_bloc = RBloc();
 _bloc.progressStateStream;