如何在Flickable中拥有GridLayout的粘性标头

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Sticky Header in Flickable'),
        ),
        body: MyHomePage(),
      ),
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return CustomScrollView(
      slivers: <Widget>[
        SliverAppBar(
          title: Text('Header'),
          pinned: true, // 设置为true使AppBar在滚动时保持固定
        ),
        SliverGrid(
          gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
            crossAxisCount: 2, // 每行显示两个元素
            childAspectRatio: 1.0, // 子元素的宽高比
          ),
          delegate: SliverChildBuilderDelegate(
            (BuildContext context, int index) {
              return Container(
                padding: EdgeInsets.all(8.0),
                color: Colors.blue[100],
                child: Center(
                  child: Text('Item $index'),
                ),
              );
            },
            childCount: 20, // 总共的子元素数量
          ),
        ),
      ],
    );
  }
}