Apple is causing quite a bit of controversy these last weeks with the way they're handling App Store rejections and how are changing what apps are permitted in the store after they're already been allowed in the App Store.
A month ago they removed Launcher from the App Store because it launched other apps from within the Today View.
Now, today, they've asked developer James Thomson to change or remove the PCalc extension, because calculations aren't permitted in the Today View. Input is allowed, but only the main app can calculate the result.
I can see why Apple is doing this. They clearly see the (iOS) Today View as an area to display data. Appointments, tasks, weather, status reports,... Extensions that launch apps or perform actions clearly don't follow in this concept, so they aren't allowed. Why they allowed these other kinds of extensions in the first place is weird. Either there wasn't a clear policy in place when iOS 8 was launched, or they decided to implement it after the fact. I don't know.
But if they don't want this, Apple should've clearly defined these guidelines from the get go instead of altering the deal after these kind of apps and extensions have already past the App Store review process. It's bad for developers, and it's confusing to users.
And now that they block these kind of extensions within the Today View, they should give these kind of extensions another place in the system to exist. The Control Center for example would be a perfect place.
Users clearly want these kind of extensions, and they want them available system wide, so I hope Apple allows them somehow. If not in the Today View, then somewhere else.