upstream-flutter-samples/cupertino_gallery/lib/widgets/checkbox_page.dart

import 'package:flutter/cupertino.dart';

class CheckboxPage extends StatefulWidget {
  const CheckboxPage({super.key});

  @override
  State<CheckboxPage> createState() => _CheckboxPageState();
}

class _CheckboxPageState extends State<CheckboxPage> {
  bool _value = false;

  @override
  Widget build(BuildContext context) {
    return CupertinoPageScaffold(
      navigationBar: const CupertinoNavigationBar(middle: Text('Checkbox')),
      child: Center(
        child: CupertinoCheckbox(
          value: _value,
          onChanged: (value) {
            setState(() {
              _value = value!;
            });
          },
        ),
      ),
    );
  }
}