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Many people don’t realise dark mode is an accessibility feature. It’s often just considered a nice to have, a cool extra feature that power users will love. But dark mode is also a valuable accessibility feature. Some types of visual impairment can make it painful to look at bright colours, or large blocks of white might wash over the black text. Some people with dyslexia or Irlen’s Syndrome can struggle to read black text on a white background. Like almost any accessibility feature, dark mode is about providing flexibility to your users so they can use your app in the way that is most comfortable to them.
Both iOS and Android feature dark modes, and the systems will do a lot for you. You may find in some apps that you really have to do no work at all other than enabling support. But for most apps to have the best effect you will have to pick some new colours and manually check your screens.
When picking colours, don’t just use white on black, a dark grey is actually easier to read on for most people compared to black. Actually, I’d suggest the same for light mode, use a very light grey background rather than pure white. Remember to check all your text/background colour combinations for contrast to ensure they reach at least 4.5:1.
When checking your screens, the system may change some colours for you automatically which can lead to some of your elements looking weird, or just not being visible at all. So make sure you check all the content is visible comparing it to your app’s light version.
For full details on implementing dark mode in your apps check out these great guides for iOS or Android from the Ray Wenderlich team.