iPhone + In App purchase

Question

Hello,

I have a existing application and I want to implement In App purchase in this application, so that application is available freely on App Store with some locked feature and if user tries to access those locked feature, they will get some message to buy unlock those features by buying the app.

Please tell me steps to implement this or some reference where step by step guidance is available.

Answer 1

Read the In App Purchase Programming Guide.

Answer 2

UrbanAirship (http://urbanairship.com/in-app-purchase/) is what you are looking for.

Answer 3

Please someone give a reference site which explains step by step to add in app purchase in existing application. Please I need it urgently