flutter -将固定的标题添加到SliverList

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: CustomScrollView(
          slivers: <Widget>[
            SliverPersistentHeader(
              delegate: MySliverHeaderDelegate(),
              pinned: true,
            ),
            SliverList(
              delegate: SliverChildBuilderDelegate(
                (context, index) => ListTile(
                  title: Text('Item $index'),
                ),
                childCount: 20,
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class MySliverHeaderDelegate extends SliverPersistentHeaderDelegate {
  @override
  Widget build(
      BuildContext context, double shrinkOffset, bool overlapsContent) {
    return Container(
      color: Colors.blue,
      child: Center(
        child: Text(
          '固定标题',
          style: TextStyle(color: Colors.white, fontSize: 20),
        ),
      ),
    );
  }

  @override
  double get maxExtent => 100;

  @override
  double get minExtent => 100;

  @override
  bool shouldRebuild(covariant SliverPersistentHeaderDelegate oldDelegate) =>
      false;
}