Flutter等待来自firestore bool的信号

import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  bool _isLoading = true;
  bool _isSignalReceived = false;

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

  Future<void> fetchData() async {
    try {
      // 初始化Firestore实例
      final firestore = FirebaseFirestore.instance;

      // 获取指定文档数据
      final snapshot = await firestore.collection('myCollection').doc('myDocument').get();

      // 处理bool类型数据
      setState(() {
        _isSignalReceived = snapshot.data()['signal'];
        _isLoading = false;
      });
    } catch (e) {
      // 处理异常情况
      print(e);
    }
  }

  @override
  Widget build(BuildContext context) {
    if (_isLoading) {
      return CircularProgressIndicator();
    } else {
      if (_isSignalReceived) {
        return Text('收到信号');
      } else {
        return Text('未收到信号');
      }
    }
  }
}