import 'package:flutter/cupertino.dart';

void main() {
  runApp(const SlidingControlDemo());
}

class SlidingControlDemo extends StatelessWidget {
  const SlidingControlDemo({super.key});

  @override
  Widget build(BuildContext context) => const CupertinoApp(
    home: CupertinoPageScaffold(
      navigationBar: CupertinoNavigationBar(middle: SlidingControl()),
      child: Center(child: SlidingControl()),
    ),
  );
}

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

  @override
  State<SlidingControl> createState() => _SlidingControlState();
}

class _SlidingControlState extends State<SlidingControl> {
  var _value = 1;

  void _onValueChange(int? value) => value != null
      ? setState(() {
          _value = value;
        })
      : null;

  @override
  Widget build(BuildContext context) => CupertinoSlidingSegmentedControl(
    children: const {1: Text('1'), 2: Text('2')},
    groupValue: _value,
    onValueChanged: _onValueChange,
  );
}