Comment by JohnTHaller

Apple won't let apps use APIs that aren't officially approved. Officially approved APIs can't do the things that flux needs to do. So, no flux on iOS in the App Store. The flux developers put together a beta that used said APIs and made it available for sideloading. Apple killed that off as well by threatening to kill their account due to a violation of the Developer Agreement which prohibits distributing your app anywhere but the App Store. Apple will only let apps onto iOS devices via the App Store. No side loading, no direct downloads, no third party app stores.