Purchase/view content from iPhone app OR website

I'm developing a website and a companion iPhone app where users can purchase video content. I'd like to let users buy content from the iPhone app or the website, and then view their purchased content through either medium. My understanding is that the app will be rejected from the App Store unless it uses the StoreKit framework for in-app purchases, so I can't implement my own purchase backend. As far as I can tell, though, there's no such thing as a web ver开发者_运维知识库sion of the StoreKit framework.

Is there any way to make/verify "in-app purchases" from outside an app, e.g. through a website?

---

There must be, because the DC Comics/Comics/Marvel Comics apps from Comixology all do. You can purchase content either from the in-app store, or via the website. And then you can read the content both in the device or online.

Alas, I don't know how they did it. I guess that the web shop replicates the in-app purchases when you buy something: i.e., the device calls home after an in-app purchase and adds that purchase to your online account as well. And, when you buy something online, you can download it from within the app, bypassing the apple store. You can even download content in one app that was purchased in the other (they are mostly the same app with different branding)