f.lux on your iPhone – without jailbreaking
12 October 2015, 05:00
UPDATE: There’s now an official version of f.lux for iOS – and we’ve a super-simple installation guide.
f.lux is a clever app that automatically removes blue from the overall colour of your screen as the sun goes down. This helps avoid nighttime eye strain. Many people swear by f.lux when using their Mac.
f.lux or a similar app will probably never be available for iPhone because of the way such apps need to access the operating system to adjust the screen colour. However, there’s a new project called GammaThingy that you can “sideload“ onto your iPhone, and that does the same job. No jailbreaking or hacks are required, although you need to compile the app yourself and then transfer it via a USB cable to your device. This is surprisingly quick and easy to do. Thanks go to YouTuber yannip1234 for showing this was possible.
Here’s the steps.
- Open the App Store ON YOUR MAC and then search for and download Xcode. It’s free although a hefty 3-4GB download. Once Xcode has finished downloading, run it once so it can finish setting-up completely. Note that you can uninstall Xcode once you’ve finished the steps below.
- Visit the GammaThingy page and download the project by clicking the Download Zip link at the right.
- Decompress the zip file you downloaded, open its folder, and then double-click the GammatTest.xcodeproject file. This will open it in Xcode.
- Within the Xcode window, click on the GammaTest folder on the left of the screen, then on the right of the screen change the text in the Bundle Identifier text field to read com.mkf.GammaTest.
- If a Fix Issue button appears a little further down, click it. You will then be prompted to add an account, after which you should sign in with your Apple ID, and then choose this account when prompted. Then attach your iPhone via USB when asked to add your device to a team, and click the Done button.
- At the top left of the toolbar, select your iPhone from the dropdown list next to the GammaTest entry, as shown here:
- Click the Play button at the left of the toolbar. The app will then be copied across to your iPhone, which will take a few minutes to complete. Watch the progress display at the top of the screen. In my test I needed to click the Play button a second time after the first build apparently completed, for the app to be copied across.
- Open the Settings app on your iPhone, click General > Profile, and then click the Trust button alongside your Apple ID.

Note that you might be prompted to tap Trust on the screen of your iPhone when attaching it for use with Xcode. This is fine.
Following this you’ll find the Gamma Test app on your home screen, and can set it up how you wish. It’s pretty easy and obvious to use.
To remove the app at a future date, first open it and click the switch next to Enabled so that the app is no longer adjusting the colour of the screen. Then open Settings, click General > Profile, select your Apple ID, and click the Delete App entry.
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