How to update a free version of App with Paid version of same app from the app in iPhone apps?

I am developing an which requires up-gradation of App from free app to paid app in free application itself. i want to lock some features in Free app and if user wants to access locked things t开发者_如何学运维hey have to download paid app by tapping on the "Update to full version" button in application itself.

I am thinking that this feature can be possible with In App purchase only. but shall I have two versions(Free, paid) or without need of two versions can I achieve this.

one more thing is how can I find whether the App is Free or paid user is using Free or paid in my application.

some please provide some detailed information, some help is very pleased to me.

Thanks in Advance.

You can do this using a single version of your application. Simply create an InApp purchase product like 'goldversion unlock' and implement the buy of this product within your application following the InApp purchase guide from Apple. Once the user has bought the upgrade, keep that settings using NSUserDefaults for example.

also check at this post for more info