Microsoft does not appear keen to pay Apple the 30% cut, as it lasts in perpetuity, regardless of whether a user continues to use an iOS device or not, as the billing is through their Apple account.
So. I know this is harsh. Don’t use SkyDrive (on iOS).
Amazon had to remove their book purchasing integration in the Kindle app on iOS too. That’s why I always found it half baked. I wanted to be able to browse books I could buy, but clearly, I was deluded for that’s not Apple’s way. Android has it better, you can browse for books and you can use SkyDrive all you want. Microsoft knew full well what the implications were going into the iOS market — they had only look to Amazon and Kindle.