AppBar 自定义顶部导航按钮 图标、颜色 以及 TabBar 定义顶部 Tab 切换

import ‘package:flutter/material.dart‘;

class ClassIf extends StatelessWidget{
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return DefaultTabController(
      length: 2,
      child: Scaffold(
        appBar: AppBar(
          title: Row( // 或者buttom
            children: <Widget>[
              Expanded(
                flex: 1,
                child: TabBar(
                  tabs: <Widget>[
                      Tab(text: ‘分类一‘),
                      Tab(text: ‘分类二‘)
                    ],
                  ),
              )
            ],
          ),
        ),
        body: TabBarView(
          children: <Widget>[
            ListView(
              children: <Widget>[
                Text(‘132‘),
                Text(‘132‘),
                Text(‘132‘),
              ],
            ),
            ListView(
              children: <Widget>[
                Text(‘132‘),
                Text(‘132‘),
                Text(‘132‘),
              ],
            )
          ],
        ),
      ),
    );
  }
}