How to detect dark mode in iOS

Swift version: 5.1

Paul Hudson @twostraws June 4th 2019

If you need to take specific action depending on whether your user is running in light mode or dark mode – for example, doing some different drawing – then you should query the userInterfaceStyle of your view controller’s trait collection.

For example, this will print one of two messages when the user taps the screen depending on whether the device is set to light mode or dark mode:

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    if traitCollection.userInterfaceStyle == .light {
        print("Light mode")
    } else {
        print("Dark mode")
    }
}