坑🕳列表

创建一个无限滚动的 ListView，创建不定长度的列表，动态更新ListView可以使用
ListView 的 builder 工厂构造器：

import 'package:flutter/material.dart';

void main() {
  runApp(new SampleApp());
}

class SampleApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Sample App',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new SampleAppPage(),
    );
  }
}

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

  @override
  _SampleAppPageState createState() => new _SampleAppPageState();
}

class _SampleAppPageState extends State<SampleAppPage> {
  List widgets = [];

  @override
  void initState() {
    super.initState();
    for (int i = 0; i < 100; i++) {
      widgets.add(getRow(i));
    }
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("Sample App"),
      ),
      body: new ListView(children: widgets),
    );
  }

  Widget getRow(int i) {
    return new GestureDetector(
      child: new Padding(
          padding: new EdgeInsets.all(10.0),
          child: new Text("Row $i")),
      onTap: () {
        setState(() {
          widgets = new List.from(widgets);
          widgets.add(getRow(widgets.length + 1));
          print('row $i');
        });
      },
    );
  }
}

// 代码作者：catsuo，链接：https://juejin.im/post/5aa17a156fb9a028c22a5b3d