let label = UILabel()

if #available(iOS 13.0, *) {
	label.textColor = .label
} else {
	label.textColor = .black
}

// Use UIAppleColor
label.textColor = UIColor.apple.label

public extension UIColor {
    static let apple: UIAppleColor
}

public struct UIAppleColor {
    var systemBackground: UIColor
    var secondarySystemBackground: UIColor
    var tertiarySystemBackground: UIColor

    var systemGroupedBackground: UIColor
    var secondarySystemGroupedBackground: UIColor
    var tertiarySystemGroupedBackground: UIColor

    var systemFill: UIColor
    var secondarySystemFill: UIColor
    var tertiarySystemFill: UIColor
    var quaternarySystemFill: UIColor

    var lightText: UIColor
    var darkText: UIColor
    var label: UIColor
    var secondaryLabel: UIColor
    var tertiaryLabel: UIColor
    var quaternaryLabel: UIColor

    var link: UIColor
    var placeholderText: UIColor
    var separator: UIColor
    var opaqueSeparator: UIColor

    var systemRed: UIColor
    var systemGreen: UIColor
    var systemBlue: UIColor
    var systemOrange: UIColor
    var systemYellow: UIColor
    var systemPink: UIColor
    var systemPurple: UIColor
    var systemTeal: UIColor
    var systemIndigo: UIColor
    var systemGray: UIColor
    var systemGray2: UIColor
    var systemGray3: UIColor
    var systemGray4: UIColor
    var systemGray5: UIColor
    var systemGray6: UIColor
}

// once in the first time
UIAppleColor.setup(mode: .dark)

let label = UILabel()
label.textColor = UIColor.apple.label

let label = UILabel()
label.textColor = UIColor.apple.mode(.dark).label