Open the youtube app from flutter app on iOS

I basically want to open a specific youtube video from my app, when a button is pressed. If the youtube app is installed on the user's device, then the video should be opened in the youtube app (and not in the browser or a separate webview).

I used the url_launcher package for that, and it works fine on android. However on iOS the youtube app is not opened even if it is installed, instead a separate web window is opened, where the corresponding youtube url is shown as a webpage.

I thought, that I could override this behaviour like so:

_launchURL() async {
  if (Platform.isIOS) {
    if (await canLaunch('youtube://www.youtube.com/channel/UCwXdFgeE9KYzlDdR7TG9cMw')) {
      await launch('youtube://www.youtube.com/channel/UCwXdFgeE9KYzlDdR7TG9cMw');
    } else {
      if (await canLaunch('https://www.youtube.com/channel/UCwXdFgeE9KYzlDdR7TG9cMw')) {
        await launch('https://www.youtube.com/channel/UCwXdFgeE9KYzlDdR7TG9cMw');
      } else {
        throw 'Could not launch https://www.youtube.com/channel/UCwXdFgeE9KYzlDdR7TG9cMw';
      }
    }
  } else {
    const url = 'https://www.youtube.com/channel/UCwXdFgeE9KYzlDdR7TG9cMw';
    if (await canLaunch(url)) {
      await launch(url);
    } else {
      throw 'Could not launch $url';
    }
  }
}

but it didn’t work. In case you wonder, I use the following imports:

import 'dart:io' show Platform;
import 'package:url_launcher/url_launcher.dart';

I am pretty sure, the youtube:// URL-Scheme works (launches the YouTube app), because I tested it on third party apps (Launch Center Pro and Pythonista).

The last thing I was not able to test, is if the Platform.isIOS is really true on my IPhone.

Is there a working way, to open the YouTube App from flutter?