I’m in my living-room, after a long day spent at the computer. It’s late night, and I’ve just finished watching something on TV. The only light comes from a small lamp on the dining table across the room. I’m comfortable on the sofa, and my iPhone is right next to me. This is the typical moment in a day where I catch up a bit on some reading — it might be an ebook, or RSS feeds, or Twitter. I wake the iPhone… and I’m glad I was able to sideload f.lux before Apple asked the developers to stop providing this option. Thanks to the altered screen colour temperature, f.lux makes reading a strain-free experience for my eyes, and I’ve finally stopped going to bed with tired, teary eyes from too much looking at the iPhone or iPad screen at night.

f.lux is an essential utility (I’ve previously mentioned it here among other essentials) that I’ve been using on the Mac since day one. What it does is described in very simple language on f.lux home page:

Ever notice how people texting at night have that eerie blue glow?

Or wake up ready to write down the Next Great Idea, and get blinded by your computer screen?

During the day, computer screens look good—they’re designed to look like the sun. But, at 9PM, 10PM, or 3AM, you probably shouldn’t be looking at the sun.

f.lux fixes this: it makes the color of your computer’s display adapt to the time of day, warm at night and like sunlight during the day.

It’s even possible that you’re staying up too late because of your computer. You could use f.lux because it makes you sleep better, or you could just use it just because it makes your computer look better.

f.lux makes your computer screen look like the room you’re in, all the time. When the sun sets, it makes your computer look like your indoor lights. In the morning, it makes things look like sunlight again.

Tell f.lux what kind of lighting you have, and where you live. Then forget about it. f.lux will do the rest, automatically.

This isn’t hype — f.lux works. It works as advertised, and it’s great. I’m a night owl, I write a lot at night because it’s peaceful and I can concentrate better. Before using f.lux on my Macs, I always went to bed with red, teary, sore eyes. The strain was perceivable, and I had to take frequent breaks and turn the desk lamp off for a bit. And when I had to stay up until the wee hours of the morning, I never ended up sleeping very well, either. After installing f.lux, everything changed instantly. At first it was strange to look at the altered colour temperature of the Mac’s screen, but I adjusted quickly, and the eye strain disappeared right away. As I’ve often said, f.lux saved my eyes.

Now, for technical reasons f.lux cannot be made available for iOS through canonical means. As the developers have written, f.lux cannot ship an iOS App using the Documented APIs, because the APIs we use are not there. If you wanted f.lux on your iOS device, you had to jailbreak it — something I didn’t want to do on my iPhone because, as much as I love f.lux, not jailbreaking my iPhone is more important to me.

Imagine my joy when the other day I saw on f.lux’s site new instructions for installing f.lux on iOS devices without jailbreaking. f.lux’s developers made available an Xcode project to download, and the idea was basically to use Xcode 7 to compile and install f.lux directly on your device physically tethered to the Mac, as if it were an app you developed yourself. Naturally, I installed it right away. The app is in beta state, but so far I haven’t had a single problem with it, and it works like a charm.

This photo I quickly took with my iPad shows the difference in colour temperature between my iPhone 4 (without f.lux) and iPhone 5 (with f.lux). I took the photo with just one dim lamp as light source. Notice how harsh the whites on the iPhone 4 are, especially in the top rows of apps and in app icons with lots of white (Calendar, Photos, VSCO Cam, Notes); so harsh that the iPad’s camera struggled to focus properly. It’s not a great photo overall, I’m aware of that, but it perfectly renders the different impact the two screens have on my eyes at night.

Of course the news spread rapidly. Of course it didn’t take long before Apple intervened and urged f.lux’s developers to stop making available f.lux this way.

Well, I urge Apple to reconsider and look the other way, or to work with f.lux’s developers to find a way to allow them to ship a regular iOS app. It saddens me that something this useful is not allowed on the App Store, while a generous quantity of utter, useless crap is. If you read a lot on your iOS devices in the evening and at night, f.lux has a really beneficial impact on your health: it leads to much less eye strain and a better sleep. It deserves a place on iOS.