Dropbox is one of the most popular cloud-based storage solutions, and many iPhone apps tie into it. This may stop soon, as Apple has decided these apps violate its guidelines for third-party software.
Everything that appears in the App Store must pass through Apple’s approval process. There is a stringent set of guidelines, and one of the most strongly enforced rules is that apps can not offer any for sale to users that doesn’t come through the iTunes store, so Apple can get its 30% share. It’s for violations of this rule that the Dropbox-related programs are being rejected for.
Under some circumstances, users of the iPhone software in question are being re-directed to a web page where they have the option buy additional storage directly from Dropbox. Any time this happens during the approval process for an app, it is rejected by Apple, and the developer is told:
We found that your app provides access to external mechanisms for purchases or subscriptions to be used in the app, which is not in compliance with the App Store Review Guidelines.
At this point, it’s not clear whether this means all support for Dropbox is going to disappear from iOS apps. It’s possible the cloud-hosting service will modify its system so that mobile users can’t upgrade their accounts from inside third-party software, and Apple would then stop rejecting apps that connect to this service.