【Flutter/Dart】DatePickerを表示する

import 'package:flutter/cupertino.dart'; 
import 'package:flutter/material.dart';

void main() {
  runApp(DatePickerApp());
}

class DatePickerApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: DatePickerScreen(),
    );
  }
}

class DatePickerScreen extends StatefulWidget {
  @override
  _DatePickerScreenState createState() => _DatePickerScreenState();
}

class _DatePickerScreenState extends State<DatePickerScreen> {
  DateTime? selectedDate;

  // DatePickerの表示
  void _selectDate(BuildContext context) {
    showModalBottomSheet(
      context: context,
      builder: (BuildContext builder) {
        return Container(
          height: 300,
          child: CupertinoDatePicker(
            mode: CupertinoDatePickerMode.date,
            initialDateTime: selectedDate ?? DateTime.now(),
            minimumDate: DateTime(2000),
            maximumDate: DateTime(2101),
            onDateTimeChanged: (DateTime newDateTime) {
              setState(() {
                selectedDate = newDateTime;
              });
            },
          ),
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Date Picker App'),
      ),
      body: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: <Widget>[
            Text(
              selectedDate != null
                  ? "${selectedDate!.toLocal()}".split(' ')[0]
                  : 'Select a date',
              style: TextStyle(fontSize: 55, fontWeight: FontWeight.bold),
            ),
            SizedBox(
              height: 20.0,
            ),
            DecoratedBox(
              decoration: BoxDecoration(
                color: Colors.blue, // Background color
              ),
              child: Container(
                width: 320,
                height: 48,
                child: CupertinoButton(
                  onPressed: () => _selectDate(context),
                  padding: EdgeInsets.all(0), // Remove default padding
                  child: Text(
                    'Select date',
                    style: TextStyle(
                      fontSize: 32,
                      color: Colors.white, // Text color
                    ),
                  ),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}