How to simulate dark mode on iOS Xcode Swift Playground

Question

Similar to How to use dark mode in simulator iOS 13? and How to enable Dark Mode on the Simulator?, how can you enable dark mode in the Xcode Swift Playground Live View?

Answer 1

You can test it in any view using overrideUserInterfaceStyle

As an example, you can paste this code in a playground to check it (tested in Xcode 11.3.1):

import Foundation
import PlaygroundSupport

extension UIColor {

    static var primary: UIColor {
        UIColor { trait -> UIColor in
            return trait.userInterfaceStyle == .light ? .black : .white
        }
    }

    static var secondary: UIColor {
        UIColor { trait -> UIColor in
            return trait.userInterfaceStyle == .light ? .white : .black
        }
    }
}

class DarkModeTestView: UIView {

    let label = UILabel(frame: CGRect(x: 0, y: 0, width: 375, height: 300))

    override init(frame: CGRect) {
        super.init(frame: frame)

        backgroundColor = .secondary

        label.text = "This text should be displayed in black for light mode and white for dark mode"
        label.textColor = .primary
        label.numberOfLines = 0

        addSubview(label)
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

let testView = DarkModeTestView(frame: CGRect(x: 0, y: 0, width: 375, height: 300))
testView.overrideUserInterfaceStyle = .dark // Change here .light or .dark

PlaygroundPage.current.liveView = testView