在哪里定义命名参数'sliver'

Question

所以，我正在创建一个基于qlixswpoi的基于银条的AppBar我找到的例子，我正面临着错误this。

我的代码有点像这样（我知道我可能把条子放在错误的地方，但是理解这个问题的任何帮助都表示赞赏）。

named parameter 'slivers' isn't defined

Answer 1

确实

Widget build(BuildContext context) {
return Scaffold(
  backgroundColor: Colors.white,
  floatingActionButton: FloatingActionButton(
    backgroundColor: Colors.white,
    onPressed: () {},
    child: Icon(
      CommunityMaterialIcons.plus,
      color: Colors.black,
    ),
  ),
  slivers: <Widget>[ // *problematic sliver here*
    SliverAppBar(
      pinned: true,
      expandedHeight: 256.0,
      flexibleSpace: FlexibleSpaceBar(
        title: Text('po.'),
      ),
    ),
  ],
  body: ListView.builder(
  itemCount: tracks.length,
  itemBuilder: (BuildContext context, int index) { // the rest of the itembuilder continued here

字段没有为slivers定义。像qzxswpoi一样包装appbar和listview，如下所示：

Scaffold

---

以下是您提供的固定要点：

NestedScrollView

Answer 2

在体内你冷设置一个SliverList并将子计数设置为0.类似于：

Widget build(BuildContext context) => Scaffold(
        backgroundColor: Colors.white,
        floatingActionButton: FloatingActionButton(
          backgroundColor: Colors.white,
          onPressed: () {},
          child: Icon(
            Icons.plus_one,
            color: Colors.black,
          ),
        ),
        body: NestedScrollView(
            headerSliverBuilder:
                (BuildContext context, bool innerBoxIsScrolled) {
              return <Widget>[
                SliverAppBar(
                  pinned: true,
                  expandedHeight: 256.0,
                  flexibleSpace: FlexibleSpaceBar(
                    title: Text('po.'),
                  ),
                ),
              ];
            },
            body: ListView.builder(
              padding: EdgeInsets.all(8.0),
              itemExtent: 20.0,
              itemBuilder: (BuildContext context, int index) {
                return Text('entry $index');
              },
            )));

通常我用

import 'package:flutter/material.dart';

void main() {
  runApp(MaterialApp(
    theme: ThemeData.dark(),
    debugShowCheckedModeBanner: false,
    home: Home(),
  ));
}

class Home extends StatelessWidget {
  final tracks = const [
    {'title': 'BCS Examination', 'subtitle': 'Something'},
    {'title': 'Dhaka University Admission'},
    {'title': 'Khulna University Admission'},
    {'title': 'Chottogram University Admission'},
    {'title': 'Bank Job Exam'},
    {'title': 'Bank Job Exam'}
  ];

  @override
  Widget build(BuildContext context) => Scaffold(
      floatingActionButton: FloatingActionButton(
        backgroundColor: Colors.white,
        onPressed: () {},
        child: Icon(
          Icons.info,
          color: Colors.black,
        ),
      ),
      body: NestedScrollView(
        headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
          return <Widget>[
            SliverAppBar(
              pinned: true,
              expandedHeight: 256.0,
              flexibleSpace: FlexibleSpaceBar(
                title: Text('po.'),
              ),
            ),
          ];
        },
        body: ListView.builder(
            itemCount: tracks.length,
            itemBuilder: (BuildContext context, int index) {
              var trackTitles = tracks[index];
              return Text(trackTitles['title']);
            }),
      ));
}

使用它，但你可以尝试。