Open facebook in IOS - Validate if it exists

I am trying to validate if facebook exists before opening it, but in IOS the code does not work, it does not validate if it exists.

  openAppUrl(app: string, name: string, id?: string) {
    switch (app) {
        case 'facebook':
            this.launchApp(
              'fb://',
              'com.facebook.katana',
              'fb://profile/' + id,
              'fb://page/' + id,
              'https://www.facebook.com/' + name);
            break;
        case 'instagram':
            this.launchApp(
              'instagram://',
              'com.instagram.android',
              'instagram://user?username=' + name,
              'instagram://user?username=' + name,
              'https://www.instagram.com/' + name);
            break;
        case 'twitter':
            this.launchApp(
              'twitter://',
              'com.twitter.android',
              'twitter://user?screen_name=' + name,
              'twitter://user?screen_name=' + name,
              'https://twitter.com/' + name);
            break;
        case 'youtube':
            this.launchApp(
              'youtube://',
              'com.google.android.youtube',
              'https://www.youtube.com/channel/' + name,
              'https://www.youtube.com/channel/' + name,
              'https://www.youtube.com/channel/' + name);
            break;
        default:
            break;
      }
  }

  private launchApp(iosApp: string, androidApp: string, appUrlIOS: string, appUrlAndroid: string, webUrl: string) {
    let app: string;
    let appUrl: string;

    if (this.platform.is('ios')) {
      app = iosApp;
      appUrl = appUrlIOS;
    } else if (this.platform.is('android')) {
      app = androidApp;
      appUrl = appUrlAndroid;
    } else {
      const browser: InAppBrowserObject = this.iab.create(webUrl, '_system');
      return;
    }
    this.appAvailability.check(app).then(
        () => {
            // success callback, the app exists and we can open it
            const browser: InAppBrowserObject = this.iab.create(appUrl, '_system');
        },
        () => {
            // error callback, the app does not exist, open regular web url instead
            const browser: InAppBrowserObject = this.iab.create(webUrl, '_system');
        }
    );
  }