Are there any additional cost for iOS?
Your reseller subscription allows you to build an unlimited number of iOS apps. GoodBarber does not charge any additional fees for iOS apps that are distributed outside of the App Store, as part of the Apple Developer Enterprise Program. On the other hand, if you want to distribute apps in the App Store, GoodBarber will charge a verification fee of $99 per app.
How do my clients manage their apps?
You give your customers access to their app backend, choosing exactly which sections you want them to contribute to and which ones you want to restrict the access to. Sending push notifications, monitoring stats, creating ad campaigns, publishing content...it is your call to decide which pages you want them to see.