如何将searchBar放入appBar - Flutter？

import 'package:flutter/material.dart';

class CustomSearchDelegate extends SearchDelegate {
  @override
  List<Widget> buildActions(BuildContext context) {
    // 在搜索栏右侧显示的操作按钮，比如清除按钮
    return [
      IconButton(
        icon: Icon(Icons.clear),
        onPressed: () {
          query = '';
        },
      ),
    ];
  }

  @override
  Widget buildLeading(BuildContext context) {
    // 在搜索栏左侧显示的返回按钮
    return IconButton(
      icon: Icon(Icons.arrow_back),
      onPressed: () {
        close(context, null);
      },
    );
  }

  @override
  Widget buildResults(BuildContext context) {
    // 在搜索结果页面显示的内容
    return Center(
      child: Text('搜索结果：$query'),
    );
  }

  @override
  Widget buildSuggestions(BuildContext context) {
    // 在搜索栏下方显示的建议内容
    return ListView(
      children: [
        ListTile(
          title: Text('建议1'),
          onTap: () {
            query = '建议1';
            showResults(context);
          },
        ),
        ListTile(
          title: Text('建议2'),
          onTap: () {
            query = '建议2';
            showResults(context);
          },
        ),
      ],
    );
  }
}

AppBar(
  title: Text('App标题'),
  actions: [
    IconButton(
      icon: Icon(Icons.search),
      onPressed: () {
        showSearch(
          context: context,
          delegate: CustomSearchDelegate(),
        );
      },
    ),
  ],
)