Yes, Night Shift. I was under the impression that Apple was releasing a version for us with older phones.Are you talking about Night Shift? If so, there's no option on older devices. You need a 64 bit (iPhone 5s or newer) to use it.
Keep in mind that for sideloading f.lux, you're going to have to go and find f.lux for Xcode yourself. In the link you provide, f.lux is no longer available as Apple notified the devs that they were in violation of their developer agreement.I haven't done this with f.lux, but I have had very good luck side-loading other projects that Apple decided I couldn't have on my 32-bit iOS devices through the App Store but ran beautifully when side-loaded.
Check it out.
https://justgetflux.com/sideload/
Or not enough. They obviously need another fix.Somebody has been watching a little too much Game of Thrones.
Keep in mind that for sideloading f.lux, you're going to have to go and find f.lux for Xcode yourself. In the link you provide, f.lux is no longer available as Apple notified the devs that they were in violation of their developer agreement.