This is the tutorial I work with so far: https://developer.xamarin.com/guides/ios/application_fundamentals/in-app_purchasing/
But I'm not able to get it to work. I want to implement the Payment Part as a DependencyService and started with iOS - because it is my main platform for mobile development. This right here is my DependencyService-Class for iOS: http://pastebin.com/R1tC8pqB and this is how I use it: http://pastebin.com/K257rLtW
But anytime I try to execute the PurchaseProductCommand or RestorePurchaseCommand I get this error: http://pastebin.com/yNUip7Z5 (sometimes it works until the login window appears but in another try it crashes instantly).
What is wrong? I can't understand it... In my opinion everything is exactly like in the "NonConsumables"-Project code from the documentation... The InApp Product is not published yet and stands on state "Waiting for transmission" but in my opinion this should not result in such a problem.