基礎子界面新增:

class AddToLogScreen extends StatelessWidget {
  @override
  Widget build (BuildContext context) {
    return CupertinoPageScaffold(
      navigationBar: CupertinoNavigationBar(
        middle: Text ('Add to Log'),
      ), // CupertinoNavigationBar
      child: Center(
        child: Text('Add to Log Screen!'),
      ),// Center
    ),// CupertinoPageScaffold
  }
}

新增:

• 增加模型獲取內容
• 將功能（新增至日誌）畫面拆分成小部件和有狀態表單

class AddToLogScreen extends Statelesswidget {
  @override
  Widget build(Bui laContext context) {
    final model = Provider.of<AppStates>(context, listen: true);

    return AdaptiveTextTheme(
      child: CupertinoPageScaffold(
        navigationBar: CupertinoNavigationBar(
          middle: Text ('Add to Log'),
        ), // CupertinoNavigationBar
        child: AddToLogForm(model.veggieById(1),(entry) {
          model.addLogEntry(entry);
          Navigator.of(context).pop();
        }),  // Center
      ),  // CupertinoPageScaffold
   );  //AdaptiveTextTheme
  }
}

typedef LogEntryCallback = void Function (LogEntry entry) ;

class AddToLogForm extends Statefulwidget {
  const AddToLogForm(this.veggie, this.onEntryCreated);
  
  final Veggie veggie;

  final LogEntryCallback onEntryCreated;
  
  @override
  _AddToLogFormState createState () => _AddToLogFormState() ;
}

class _AddToLogFormState extends State<AddToLogForm> {
  @override
  Widget build(BuildContext context) {
  final textTheme = AdaptiveTextTheme. of(context);
  
  return  SizedBox();

並解答如何將業務邏輯與表示邏輯分開？
當中使用螢幕小工具(AddToLogScreen)，為管理與模型的活動。實際上會從中讀取數據並將數據保存其中有咩。

另一個小部件(_AddToLogFormState)負責表單的外觀和界面表現方式