Cupertino_tab_view_bug.dart

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

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

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

  @override
  Widget build(BuildContext context) {
    return CupertinoApp(
        theme: CupertinoThemeData(
          brightness: Brightness.light,
          primaryColor: CupertinoColors.destructiveRed,
          primaryContrastingColor: CupertinoColors.white,
          scaffoldBackgroundColor: CupertinoColors.white,
          barBackgroundColor: CupertinoColors.white.withOpacity(0.4),
        ),
        builder: (context, x) => CupertinoTabScaffold(
            tabBar: CupertinoTabBar(
              items: const [
                BottomNavigationBarItem(
                  icon: Icon(CupertinoIcons.home),
                  label: 'Demo',
                ),
                BottomNavigationBarItem(
                  icon: Icon(CupertinoIcons.home),
                  label: 'Other Demo',
                ),
              ],
            ),
            tabBuilder: (context, index) => Home()));
  }
}

class Home extends StatefulWidget {
  const Home({Key? key}) : super(key: key);

  @override
  State<Home> createState() => _HomeState();
}

class _HomeState extends State<Home> {
  bool useTabView = false;

  @override
  Widget build(BuildContext context) {
    return SafeArea(
      child: Column(
        children: [
          CupertinoButton(
              child: const Text("Toggle"),
              onPressed: () => setState(() => useTabView = !useTabView)),
          Expanded(
              child: useTabView
                  ? CupertinoTabView(
                      builder: (context) =>
                          const Center(child: Text("With Tabview")))
                  : const Center(child: Text("Without Tabview")))
        ],
      ),
    );
  }
}