How to detect if OS X is in dark mode?

Question

My cocoa app has to change its behaviour when run in the new OS X "dark mode".

Is there a way to detect if OS X style is set to this mode?

Answer 1

Don't think there's a cocoa way of detecting it yet, however you can use defaults read to check whether or not OSX is in dark mode.

defaults read -g AppleInterfaceStyle

Either returns Dark (dark mode) or returns domain pair does not exist.

EDIT:

As Ken Thomases said you can access .GlobalPreferences via NSUserDefaults, so

NSString *osxMode = [[NSUserDefaults standardUserDefaults] stringForKey:@"AppleInterfaceStyle"];

If osxMode is nil then it isn't in dark mode, but if osxMode is @"Dark" then it is in dark mode.

Answer 2

Swift 2 -> String ("Dark", "Light")

let appearance = NSUserDefaults.standardUserDefaults().stringForKey("AppleInterfaceStyle") ?? "Light"

Swift 3 -> Enum (Dark, Light)

enum InterfaceStyle : String {
   case Dark, Light

   init() {
      let type = UserDefaults.standard.string(forKey: "AppleInterfaceStyle") ?? "Light"
      self = InterfaceStyle(rawValue: type)!
    }
}

let currentStyle = InterfaceStyle()

Answer 3

You can detect this using NSAppearanceCustomization method effectiveAppearance, by checking for darkAqua.

Swift 4 example:

extension NSView {
    var isDarkMode: Bool {
        if #available(OSX 10.14, *) {
            if effectiveAppearance.name == .darkAqua {
                return true
            }
        }
        return false
    }
}

Answer 4

You can also wrap it in a boolean if you don't feel like dealing with enums and switch statements:

/// True if the application is in dark mode, and false otherwise
var inDarkMode: Bool {
    let mode = UserDefaults.standard.string(forKey: "AppleInterfaceStyle")
    return mode == "Dark"
}

Works on Swift 4.2

Answer 5

For working with the new macOS Catalina you need to combine AppleInterfaceStyle with this new value introduced AppleInterfaceStyleSwitchesAutomatically.

Here is some pseudo-code explaining how to:

theme = light //default is light
if macOS_10.15
    if UserDefaults(AppleInterfaceStyleSwitchesAutomatically) == TRUE
        if UserDefaults(AppleInterfaceStyle) == NIL
            theme = dark // is nil, means it's dark and will switch in future to light
        else
            theme = light //means it's light and will switch in future to dark
        endif
    else
        if UserDefaults(AppleInterfaceStyle) == NIL
            theme = light
        else
            theme = dark
        endif
    endif
else if macOS_10.14
    if UserDefaults(AppleInterfaceStyle) == NIL
        theme = light
    else
        theme = dark
    endif
endif

You can check a macOS sample app here: https://github.com/ruiaureliano/macOS-Appearance.

(Disclaimer: I am the author of this sample app.)