[jonah]

So, what is it doing that f.lux isn't/can't on non-jailbroken phones? I know they'd need access to APIs that Apple doesn't make available.

[wingerlang]

I haven't looked into it, but I would assume it is hooking into private frameworks and this is simply not allowed from an app on the App Store.

[stevetrewick]

Yes, it uses IOKit which is a private API on iOS.