Few years ago before Apple implemeted Night Shift, F.lux used to use an ability for non-paid developer accounts to compile and run an app on their phone to dist

Few years ago before Apple implemeted Night Shift, F.lux used to use an ability for non-paid developer accounts to compile and run an app on their phone to distribute. They provided a source code for a small program that serve as a shim to F.lux. User need to compile this code with Xcode and put it on their phone. People followed tutorial videos downloading Xcode, making a developer account, figure out how to get signing profile works, etc. just to get F.lux installed on their phone. Searching for "Flux iOS 9" on YouTube yields some video with over 100k views. In some community there are people who are willing to do it for you (by VNC into user's machine) at $10 per installation.