Detecting iOS Dark Mode Change

Question

I read through the documentation regarding: https://developer.apple.com/documentation/appkit/supporting_dark_mode_in_your_interface

When the user chan

Answer 1

in iOS Swift 5

override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
  // Do sonthing
}

Answer 2

I ended up moving all my color setup to layoutSubviews() function in all views and the viewDidLayoutSubviews() in the view controllers.

Answer 3

Just override method form iOS 13 to Detect dark light mode change swift 5

override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
    super.traitCollectionDidChange(previousTraitCollection)

    if #available(iOS 13.0, *) {
        if self.traitCollection.hasDifferentColorAppearance(comparedTo: previousTraitCollection) {
            if traitCollection.userInterfaceStyle == .dark {
                //Dark
            }
            else {
                //Light
            }
        }
    } else {
        // Fallback on earlier versions
    }
}

traitCollectionDidChange is a method in ViewControllers and Views.

Answer 4

Objective-C version:

if (@available(iOS 12.0, *)) {

    if( self.traitCollection.userInterfaceStyle == UIUserInterfaceStyleDark ){
       //is dark
    }else{
        //is light

    }
}

Answer 5

Swift 5:

traitCollectionDidChange also gets called a few times. This is how I detect DarkMode runtime change and setColors() only once.

override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
        super.traitCollectionDidChange(previousTraitCollection)

        guard UIApplication.shared.applicationState == .inactive else {
            return
        }

        setColors()
    }

In setColors() func I update the colors. Detecting current colorScheme:

extension UIViewController {
    var isDarkMode: Bool {
        if #available(iOS 13.0, *) {
            return self.traitCollection.userInterfaceStyle == .dark
        }
        else {
            return false
        }
    }

}

I have colors defined like this (for iOS < 13):

enum ColorCompatibility {
    static var myOlderiOSCompatibleColorName: UIColor {
        if UIViewController().isDarkMode {
            return UIColor(red: 33, green: 35, blue: 37, alpha: 0.85)
        }
        else {
            return UIColor(hexString: "#F3F3F3", alpha: 0.85)
        }
    }
}

Example:

private func setColors() {
  myView.backgroundColor = ColorCompatibility.myOlderiOSCompatibleColorName
}

Also you might need to call setColors in ViewDidLoad/Will/DidAppear depending on your case like this:

viewDidLoad() {
...
setColors()
...
}

For iOS11+ you could use "named Colors", defined in Assets and much easier to use in IB.

Cheers

Answer 6

I think for colors is better to use

UIColor.init { (trait) -> UIColor in

    return trait.userInterfaceStyle == .dark ? .label : .black
}

because this way if the system change, the color change too automatically.