I made a class for exactly this purpose. It checks the validity of the current subscription and returns a bool value whether you want to show content or not, and also saves the current subscription info.
Please take a look and tell me if it helped.
Here is the class.
Edit
Yes, the user has to give the password every time the user purchases a subscription.
Or else if the user deletes the app, then again installs the application. The class will know that a purchase has been made prior or not, ONLY if iTunes is logged in.
- To know purchases items iTunes has to be logged in from settings, hence uninstalling an app is not a problem.
- To purchase a product, subscription, the password is needed to enter every time by the user
I have created this application using this class, so I can tell you, it follows the IN APP purchase guidelines by Apple.
I will upload an example project in Github, soon.