iOS In-App Purchase - internal or external content?

Question

I'm trying to wrap my head around in-app purchase and still don't get it... :/ I'm writing small app for children to learn the alphabet, how do I lock let say half of the letters? Do I need to just sell permissions to unlock in-app content or I should leave only free content and throw out of the app the part which I want to sell? And if I do throw out is there an easy way to control which images/sounds etc to display? Quite messy stuff, at least for noob ;)

Answer 1

Yes, you can just sell boolean value that you store, for example, at your NSUserDefaults, and check if a customer bought a full pack. Then let him use it.

Answer 2

You can create category and sell category like color (Red, green...), Object (pen, tea..) and so on and sell this category. or just show free content and in the place of paid content show alert for buying.