UIColor enhancements

UIColor.swift

extension UIColor {
    //
    // MARK: create with hex string
    //

    convenience init(string: String) {
        // strip leading pound
        let s = string.stringByReplacingOccurrencesOfString("#", withString: "")

        var r = UInt32(0)
        var g = UInt32(0)
        var b = UInt32(0)
        var a = UInt32(0xff)

        var value = UInt32(0)
        NSScanner(string: s).scanHexInt(&value)

        switch s.length {
        case 2:
            r = value
            g = value
            b = value

        case 3:
            // RGB
            r = (value & 0xf00) >> 8
            g = (value & 0x0f0) >> 4
            b = (value & 0x00f) >> 0
            r += r * 16
            g += g * 16
            b += b * 16

        case 6:
            // RRGGBB
            r = (value & 0xff0000) >> 16
            g = (value & 0x00ff00) >>  8
            b = (value & 0x0000ff) >>  0

        default:
            // RRGGBBAA
            r = (value & 0xff000000) >> 24
            g = (value & 0x00ff0000) >> 16
            b = (value & 0x0000ff00) >>  8
            a = (value & 0x000000ff) >>  0
        }

        self.init(red: CGFloat(r) / CGFloat(255), green: CGFloat(g) / CGFloat(255), blue: CGFloat(b) / CGFloat(255), alpha: CGFloat(a) / CGFloat(255))
    }

    //
    // MARK: components
    //

    var hue: CGFloat {
        get {
            var value = CGFloat(0)
            getHue(&value, saturation: nil, brightness: nil, alpha: nil)
            return value
        }
    }
    var saturation: CGFloat {
        get {
            var value = CGFloat(0)
            getHue(nil, saturation: &value, brightness: nil, alpha: nil)
            return value
        }
    }
    var brightness: CGFloat {
        get {
            var value = CGFloat(0)
            getHue(nil, saturation: nil, brightness: &value, alpha: nil)
            return value
        }
    }
    var red: CGFloat {
        get {
            var value = CGFloat(0)
            getRed(&value, green: nil, blue: nil, alpha: nil)
            return value
        }

    }
    var green: CGFloat {
        get {
            var value = CGFloat(0)
            getRed(nil, green: &value, blue: nil, alpha: nil)
            return value
        }

    }
    var blue: CGFloat {
        get {
            var value = CGFloat(0)
            getRed(nil, green: nil, blue: &value, alpha: nil)
            return value
        }

    }
    var alpha: CGFloat {
        get {
            var value = CGFloat(0)
            getRed(nil, green: nil, blue: nil, alpha: &value)
            return value
        }
    }

    //
    // MARK: HSB
    //

    /*
    func lighten(percent: CGFloat) -> UIColor {
        return offsetHSB(brightness: percent)
    }

    func darken(percent: CGFloat) -> UIColor {
        return offsetHSB(brightness: -percent)
    }
    */

    func offset(hue: CGFloat = 0, saturation: CGFloat = 0, brightness: CGFloat = 0, alpha: CGFloat = 0) -> UIColor {
        var h = CGFloat(0), s = CGFloat(0), b = CGFloat(0), a = CGFloat(0)
        getHue(&h, saturation: &s, brightness: &b, alpha: &a)

        func clamp(x: CGFloat) -> CGFloat {
            return min(max(x, CGFloat(0)), CGFloat(1))
        }

        h = (h + hue) % CGFloat(1)
        s = clamp(s + saturation)
        b = clamp(b + brightness)
        a = clamp(a + alpha)

        return UIColor(hue: h, saturation: s, brightness: b, alpha: a)
    }

    //
    // MARK: with
    //

    func with(#red: CGFloat) -> UIColor {
        var ignore = CGFloat(0), green = CGFloat(0), blue = CGFloat(0), alpha = CGFloat(0)
        getRed(&ignore, green: &green, blue: &blue, alpha: &alpha)
        return UIColor(red: red, green: green, blue: blue, alpha: alpha)
    }
    func with(#green: CGFloat) -> UIColor {
        var red = CGFloat(0), ignore = CGFloat(0), blue = CGFloat(0), alpha = CGFloat(0)
        getRed(&red, green: &ignore, blue: &blue, alpha: &alpha)
        return UIColor(red: red, green: green, blue: blue, alpha: alpha)
    }
    func with(#blue: CGFloat) -> UIColor {
        var red = CGFloat(0), green = CGFloat(0), ignore = CGFloat(0), alpha = CGFloat(0)
        getRed(&red, green: &green, blue: &ignore, alpha: &alpha)
        return UIColor(red: red, green: green, blue: blue, alpha: alpha)
    }
    func with(#alpha: CGFloat) -> UIColor {
        var red = CGFloat(0), green = CGFloat(0), blue = CGFloat(0), ignore = CGFloat(0)
        getRed(&red, green: &green, blue: &blue, alpha: &ignore)
        return UIColor(red: red, green: green, blue: blue, alpha: alpha)
    }
    func with(#hue: CGFloat) -> UIColor {
        var ignore = CGFloat(0), saturation = CGFloat(0), brightness = CGFloat(0), alpha = CGFloat(0)
        getHue(&ignore, saturation: &saturation, brightness: &brightness, alpha: &alpha)
        return UIColor(hue: hue, saturation: saturation, brightness: brightness, alpha: alpha)
    }
    func with(#saturation: CGFloat) -> UIColor {
        var hue = CGFloat(0), ignore = CGFloat(0), brightness = CGFloat(0), alpha = CGFloat(0)
        getHue(&hue, saturation: &ignore, brightness: &brightness, alpha: &alpha)
        return UIColor(hue: hue, saturation: saturation, brightness: brightness, alpha: alpha)
    }
    func with(#brightness: CGFloat) -> UIColor {
        var hue = CGFloat(0), saturation = CGFloat(0), ignore = CGFloat(0), alpha = CGFloat(0)
        getHue(&hue, saturation: &saturation, brightness: &ignore, alpha: &alpha)
        return UIColor(hue: hue, saturation: saturation, brightness: brightness, alpha: alpha)
    }

    //
    // MARK: other accessors
    //

    var rgb: UInt32 {
        get {
            var red = CGFloat(0)
            var green = CGFloat(0)
            var blue = CGFloat(0)
            getRed(&red, green: &green, blue: &blue, alpha: nil)

            let r = UInt32(red   * CGFloat(255.0))
            let g = UInt32(green * CGFloat(255.0))
            let b = UInt32(blue  * CGFloat(255.0))
            return (r << 16) + (g << 8) + b
        }
    }

    var rgba: UInt32 {
        get {
            var red = CGFloat(0)
            var green = CGFloat(0)
            var blue = CGFloat(0)
            var alpha = CGFloat(0)
            getRed(&red, green: &green, blue: &blue, alpha: &alpha)

            let r = UInt32(red    * CGFloat(255.0))
            let g = UInt32(green  * CGFloat(255.0))
            let b = UInt32(blue   * CGFloat(255.0))
            let a = UInt32(alpha  * CGFloat(255.0))
            return (r << 24) + (g << 16) + (b << 8) + a
        }
    }

    var string: String {
        get {
            if alpha != CGFloat(1) {
                return NSString(format: "#%08x", rgba)
            }
            return NSString(format: "#%06x", rgb)
        }
    }
}