操作栏抽屉切换在AppBar上显示但不起作用？

import 'package:flutter/material.dart';

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  bool isDrawerOpen = false;

  void toggleDrawer() {
    setState(() {
      isDrawerOpen = !isDrawerOpen;
    });
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('My App'),
          leading: IconButton(
            icon: Icon(Icons.menu),
            onPressed: toggleDrawer,
          ),
        ),
        drawer: isDrawerOpen ? Drawer() : null,
        body: Container(
          // Your app content here
        ),
      ),
    );
  }
}