Cupertino Segmented Control implementation

cupertino_segmented_control.dart

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

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  // Cupertino Segmented Control takes children in form of Map.
  final cupertinoMap = <int, Widget>{};

  //The Widgets that has to be loaded when a tab is selected.
  late List<Widget> childWidgets;
  late List<String> cupertinoSegmentedTitles;
  int selectedIndex = 0;

  @override
  void initState() {
    super.initState();
    cupertinoSegmentedTitles = ['Upcoming', 'Live', 'Completed'];
    loadCupertinoTabs();
    loadCupertinoChildWidgets();
  }

  void loadCupertinoTabs() {
    for (var i = 0; i < 3; i++) {
      cupertinoMap.putIfAbsent(
        i,
        () => Padding(
          padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 16),
          child: Text(cupertinoSegmentedTitles[i]),
        ),
      );
    }
  }

  void loadCupertinoChildWidgets() {
    childWidgets = [];
    for (var i = 0; i < 3; i++) {
      childWidgets.add(Center(child: Text("child $i")));
    }
  }

  Widget childWidget() {
    return childWidgets.elementAt(selectedIndex);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Column(
        children: [
          CupertinoSegmentedControl<int>(
            onValueChanged: (value) => setState(() => selectedIndex = value),
            children: cupertinoMap,
            padding: const EdgeInsets.all(12),
            groupValue: selectedIndex,
            selectedColor: Colors.green,
            pressedColor: Colors.green.shade100,
            unselectedColor: Colors.white,
            borderColor: Colors.grey.shade300,
          ),
          Expanded(
            child: childWidget(),
          )
        ],
      ),
    );
  }
}