flutter_sliver_app_bar.dart

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: SamplePage(),
      ),
    );
  }
}

class SamplePage extends StatefulWidget {
  SamplePage({Key key}) : super(key: key);

  @override
  _SamplePageState createState() => _SamplePageState();
}

class _SamplePageState extends State<SamplePage>
    with SingleTickerProviderStateMixin {
  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CustomScrollView(
        slivers: <Widget>[
          SliverAppBar(
            actions: <Widget>[
              Material(
                color: Colors.transparent,
                child: InkWell(
                  onTap: () {},
                  child: IconButton(
                    icon: Icon(Icons.access_alarm),
                    onPressed: () {},
                  ),
                ),
              ),
            ],
            title: Text('SliverAppBar'),
            backgroundColor: Theme.of(context).accentColor,
            expandedHeight: 200.0,
            flexibleSpace: FlexibleSpaceBar(
              background: Container(
                decoration: BoxDecoration(
                    gradient: LinearGradient(
                  colors: [Colors.blue, Colors.green],
                )),
              ),
            ),
            // floating: floating,
            // snap: snap,
            pinned: true,
          ),
          SliverList(
            delegate:
                SliverChildBuilderDelegate((BuildContext context, int index) {
              if (index > 30) {
                return null;
              }
              return ListTile(
                title: Text('item ${index.toString()}'),
                onTap: () {},
              );
            }),
            // delegate: SliverChildListDelegate(
            //   List.generate(30, (int index) {
            //     return ListTile(title: Text('item ${index.toString()}'),onTap: (){},);
            //   }),
            // ),
          ),
        ],
      ),
    );
  }
}

https://dartpad.cn/65e608a943f2b115db87e2c438548ced