iPhone In-App Subscription purchase

I need a sample iPhone application that implements in-app purchase of a renewable susbcription and a step by step of how to re-use it and test that sample application. I never implemented in-app purchase and I need to implement it for an application so I need an Xcode project already implementing this code and also with the user interphase that ask users to buy the subscription, and the GUI for managing the subscriptions and the one to cancel the subscription.