splash_page.dart

class SplashPage extends StatelessWidget {
  final Completer<bool> completer;

  SplashPage({this.completer, Key key}) : super(key : key);

  @override
  Widget build(BuildContext context) {
    // Fetch some information from the internet.
    // When finished, complete the Completer with the `true` value
    // If there is an error, then
    http.get('https://jsonplaceholder.typicode.com/todos/1').then((_) =>
        completer.complete(true)).catchError((_) =>
        completer.complete(false));

    return Material(
      child: Container(
        color: Colors.red,
        child: Center(
          child: CircularProgressIndicator(),
        ),
      ),
    );
  }
}