• Cupertino widgets
  基於Apple Human Interface Guidelines 實現了當前的IOS設計風格.
• Provider:
  與每次創建一個新類別相比，大大減少了樣板程式碼.
  開發工具友善–使用 Provider，應用程式的狀態將在Flutter開發工具中可見.
• tabBuilder
  IndexedWidgetBuilder建構的小工具通常是CupertinoTabView，以實現具有選項卡欄的IOS應用程式上看到的平行分層資訊架構. CupertinoTabView建立單獨的導覽的根視圖.

import 'package:flutter/cupertino.dart';
import 'package:provider/provider.dart';
import 'package:veggietracker/data/models.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build (BuildContext context) {
    return ChangeNotifierProvider<AppState>(
      builder: (context) => AppState(),
      child: CupertinoApp(
        debugShowCheckedModeBanner: false,
        theme: CupertinoThemeDatal(
          primaryColor: Color(OxFFFF2D55),//紅色日誌圖示
          ),
          home: MainScreen(),
        ),
     );
   }
}
class MainScreen extends StatelessMidget {
  @override
  Widget build(BuildContext context) {
    return CupertinoTabScaffold(
      tabBar: CupertinoTabBar(
        items: [
          BottomNavigationBarItem(
            title: Text('Log'),
            icon: Icon (Cupertinolcons.book),
            ), // BottomNavigationbarItem
          BottomNavigationBariten(
            title: Text('List'),
            icon: Icon(CupertinoIcons.create), 
            ), // BottomNavigationBarItem
         ],
        ), // CupertinoTabBar
        resizeToAvoidBottomInset: false,
        tabBuilder: (context, index) {
          return(index == 0 )
              ?CupertinotabView(builder:(context) => LogScreen())
              :CupertinotabView(builder:(context) => ListScreen());
        },
    ): // CupertinoTabScaffold
   }
  }

class LogScreen extends Statelesswidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: Text('Log Screen!'),
    );
  }
}    

class Listscreen extends Statelesswidget {
  @override
  Widget build (BuildContext context) {
    return Center(
      child: Text('List Screen!'),
  }
}

class ADDtOLOGsCREEN extends Statelesswidget {
  @override
  Widget build (BuildContext context) {
    return Center(
      child: Text('Add to Log Screen!'),
    );
  }
}