To set up and use Dark Mode, open System Preferences (the app with the grey icon showing cogs), and scroll up. Tap the Display and Brightness link; it’s in the third set of links, and has a blue double-A icon.
At the top of the screen, you see the Light and Dark options; tap one to choose it, immediately making the screen light or dark. This is the option you use to change the screen mode on a permanent basis.
Under the Light and Dark pictures, there’s a switch labelled ‘Automatic’. If you want the light and dark modes to toggle automatically, turn it on by tapping this switch. Do so and an Options link appears under the Automatic switch.
By default, Options reads ‘Light Until Sunset’, meaning the iPhone is in Light Mode until the sun goes down. Tap the Options link and you’re taken to the Appearance Schedule screen. Sunset to Sunrise is selected by default.
Tap Custom Schedule and you can set specific times for activating Light Mode and Dark Mode. Tap Light Appearance, then use the wheels to set the time when the iPhone switches to Light Mode.
Tap Dark Appearance, and, by dragging the wheels up and down again, you can now set a time when Dark Mode is activated. When you’re done, tap the Back link, and the phone’s Light and Dark Mode times are set.
Dark Mode in action
With Dark Mode on, your wallpaper is swapped for a darker version. This only applies if you’ve chosen a wallpaper with a Dark Mode in System > Wallpaper, of course; they’re the ones with the Circle icon in the bottom right.
In Dark Mode, white text on a black background is favoured, as we can see on this screen from the Notes app. This might make it easier to read in very bright light, and less taxing on the eyes after darkness falls.
Apple’s own built-in apps, and an increasing amount of third-party apps, use Dark Mode when it’s activated on your iPhone. Here we see the Maps app in Dark Mode, with the background black and the street names white.