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

import 'package:flutter/cupertino.dart';

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

  @override
  Widget build(BuildContext context) {
    return const CupertinoPageScaffold(
      navigationBar: CupertinoNavigationBar(middle: Text('Activity Indicator')),
      child: Center(child: CupertinoActivityIndicator()),
    );
  }
}