An extension of the iOS class UIColor to provide conversion to and from HSV (hue, saturation, value) colors.

UIColor+HSV.swift

/// An extension to provide conversion to and from HSV (hue, saturation, value) colors.
extension UIColor {

    /// The HSV (hue, saturation, value) components of a color.
    struct HSV: Hashable {

        /// The hue component of the color, in the range [0, 360°].
        var hue: CGFloat
        /// The saturation component of the color, in the range [0, 100%].
        var saturation: CGFloat
        /// The value component of the color, in the range [0, 100%].
        var value: CGFloat

    }

    /// The HSV (hue, saturation, value) components of the color.
    var hsv: HSV {
        var (h, s, v) = (CGFloat(), CGFloat(), CGFloat())
        getHue(&h, saturation: &s, brightness: &v, alpha: nil)
        
        return HSV(hue: h * 360.0,
                   saturation: s * 100.0,
                   value: v * 100.0)
    }

    /// Initializes a color from HSV (hue, saturation, value) components.
    /// - parameter hsv: The components used to initialize the color.
    /// - parameter alpha: The alpha value of the color.
    convenience init(_ hsv: HSV, alpha: CGFloat = 1.0) {
        self.init(hue: hsv.hue / 360.0,
                  saturation: hsv.saturation / 100.0,
                  brightness: hsv.value / 100.0,
                  alpha: alpha)
    }

}