I just checked Dropbox and Google Drive apps, both offer in-app upgrade of disk storage, giving Apple 30% cut. Appears that you can not simply just remove the upgrade option from the app. So I don't see how MS could be any different.
You can't, because apple rejects your app, if it is in any way connected with a website that offers payment. In other words, apple doesn't allow you to circumvent this "30% tax" by accepting only website payments. If you accept payments, you have to accept them also on iOS. At least that was the case with our relatively new app.
Was this for content that can live outside of the app? As can the storage or perhaps the books mentioned elsewhere in the discussion. If it was something tied with app I can see why apple doesn't want you to sell it anywhere else.
>Was this for content that can live outside of the app?
I don't fully understand your question. We have a voip app that among other things allows users to call landline or mobile numbers. These calls are not free, so a user must pay. We started with web site+flash and added paypal and stripe payment options. Then we've created iOS app and as anyone else found out about 30% tax. Long story short, nothing worked until we added in app purchases. Before that, the app was continuously rejected on the grounds that if it's possible to pay on website and then use that credit on iOS app, then we must provide also in app purchases.
> I can see why apple doesn't want you to sell it anywhere else.
It's not that apple don't want you to sell it anywhere else, but that if you do sell it anywhere else, you have to sell it also on iOS.
Also wondering what's stopping MS from doing down the DropBox path and not allowing purchases on iOS.