A system-wide Night Theme would let iOS look and feel great throughout the day.

A couple of years ago Apple reimagined everything from the aesthetics to the physics of how a modern mobile operating system should look and act. Part of that involved the use of a lot of highly-scalable flat, white space. A lot, a lot.

It makes the iPhone and iPad look bold and bright, which is fine for everyday use. When it comes to low-light situations, though — like the home theater or the bedroom — that intensity is enough to get you yelled at or hit with a pillow. It's also enough to make me wish for a full-on dark mode in iOS 10

State of the night

There's currently no system-wide Night Theme in iOS. Some people use Invert Colors — part of Apple's terrific accessibility support — which does turn the interface from white to black... but also turns blue turn to orange, green turn to purple, and every color to its opposite. Including your wallpaper, your photographs, your everything.

As workarounds go, it's decidedly mediocre.

Apple's iBooks already has a proper night theme: You can manually switch it on or set it to turn on automatically at night. Rather than invert colors, it sets them appropriately for low-light conditions. It makes the white background black, the black text light gray, and blue and green tint colors the right shades of gray. Importantly, it leaves pictures, photos, and other graphics as they were, so they maintain the proper colors.

Maps can go dark as well, which helps when navigating at night.

Some App Store apps include their own Night Themes. In Fantastical, you can toggle a light mode on in the app's settings. In Tweetbot, a Twitter app, you can swipe down with two fingers to switch between light and dark modes.

Many apps don't provide the option, though, and even those that do vary in their implementations. That leads to an inconsistent experience.

Apple Watch, by contrast, has a dark interface by default. That's because it uses an OLED display. Unlike the LED of iPhone and iPad backlight, which is either all on or all off, OLED can light up only the pixels it needs. That makes black more power efficient than white, which is especially important on devices with tiny batteries like watches.

Shifting starts

With iOS 9.3, Apple is adding Night Shift to iPhone and iPad. It's a technology that gradually, over the course of the day, changes the display from cooler (blue) towards warmer (yellow) along the color spectrum. You can choose to have it happen naturally from sundown to sunrise, between any pre-set times, or you can flip the switch manually. The idea is that the warmer cast preserves melatonin build-up and suppresses histamine, which is ultimately less disruptive to sleep patterns.

That's all terrific, and it absolutely enhances the overall iPhone and iPad experience. But it doesn't address what a Night Theme would — It changes the color cast of the display but doesn't do anything to radically reduce its brightness.

A yellower light is still a light.

On the NightKit

When an environment is dark, any light will stand out all the more brightly. It becomes a beacon. It becomes neon. That's where a Night Theme comes in.

If Apple could provide a dark mode for all of its apps, it would go a long way toward making the iPhone more usable in the dark. If Apple could take it a step further, though, and provide a "NightKit" framework for its standard UIKit interface system, then any App Store app could tie into it as well.

That way customers could set Night Theme once and have it automatically or manually enabled everywhere, all at once. Like Night Shift, it could live in Settings > Display and Brightness, and be toggled on or off from Command Center at any time.

For developers, a framework could conceivably let them tweak parameters and set colors so that their app's interface looks exactly the way the developer wants in either light or dark modes.

Night riding

Android N, the next version of Google's operating system, is teasing a Night mode again. That's likely because it's one of the few low-hanging features left in a rapidly maturing market.

To nail it system-wide, and to make it work for developers as well, is no doubt a monumental task. In theory, something like CSS could be a model for a full-on theming engine. In practice, a legion of devils lurk in the implementation details.

Either way, every time I turn on my iPhone in the dark and my eyes squint for a moment as the world goes suddenly white, I'm reminded how the lack of a Night Theme remains a problem. And solving those kinds of problems is what Apple does.

I've filed this feature request with Apple. It can be found at rdar://19760524 (closed as a dupe of rdar://11786790). Do you want a system-wide night theme? Let me know!