An extension of the iOS class UIColor to provide conversion to and from ARGB (alpha, red, green, blue) colors.

UIColor+ARGB.swift

/// An extension to provide conversion to and from ARGB (alpha, red, green, blue) colors.
extension UIColor {

    /// The ARGB (alpha, red, green, blue) components of a color, in the range [0, 255].
    struct ARGB: Hashable {

        /// The alpha component of the color, in the range [0, 255].
        var alpha: Int
        /// The red component of the color, in the range [0, 255].
        var red: Int
        /// The green component of the color, in the range [0, 255].
        var green: Int
        /// The blue component of the color, in the range [0, 255].
        var blue: Int

    }

    /// The ARGB (alpha, red, green, blue) components of the color, in the range [0, 255].
    var argb: ARGB {
        var (r, g, b, a) = (CGFloat(), CGFloat(), CGFloat(), CGFloat())
        getRed(&r, green: &g, blue: &b, alpha: &a)
        
        return ARGB(alpha: Int(round(a * 255.0)),
                    red: Int(round(r * 255.0)),
                    green: Int(round(g * 255.0)),
                    blue: Int(round(b * 255.0)))
    }

    /// Initializes a color from ARGB (alpha, red, green, blue) components.
    /// - parameter argb: The components used to initialize the color.
    convenience init(_ argb: ARGB) {
        self.init(red: CGFloat(argb.red) / 255.0,
                  green: CGFloat(argb.green) / 255.0,
                  blue: CGFloat(argb.blue) / 255.0,
                  alpha: CGFloat(argb.alpha) / 255.0)
    }

}