NSColor の Component と ColorSpace について

NSColor には.whiteComponentや.redComponent、cyanComponent、hueComponentなどさまざまな色の要素の値を取得することができる変数が生えていますが、NSColor のもつ colorSpace によって取得できる component には決まりがあるようです。

ColorSpace	LocalizedName	Components	Initializer
deviceGray	Device Gray	white, alpha	NSColor(deviceWhite:alpha:)
genericGray	Generic Gray	white, alpha	NSColor(calibratedWhite:alpha:)
genericGamma22Gray, extendedGenericGamma22Gray	Generic Gray Gamma 2.2 Profile	white, alpha	NSColor(white:alpha:) NSColor(genericGamma22White:alpha:)
deviceRGB	Device RGB	red, green, blue, alpha, hue, saturation, brightness	NSColor(deviceRed:green:blue:alpha:)
genericRGB	Generic RGB	red, green, blue, alpha, hue, saturation, brightness	NSColor(calibratedRed:green:blue:alpha:)
sRGB, extendedSRGB	sRGB IEC61966-2.1	red, green, blue, alpha, hue, saturation, brightness	NSColor(red:green:blue:alpha:) NSColor(srgbRed:green:blue:alpha:)
displayP3	Display P3	red, green, blue, alpha, hue, saturation, brightness	NSColor(displayP3Red:green:blue:alpha:)
adobeRGB1998	Adobe RGB (1998)	red, green, blue, alpha, hue, saturation, brightness
deviceCMYK	Device CMYK	cyan, magenta, yellow, black, alpha	NSColor(deviceCyan:magenta:yellow:black:alpha:)
genericCMYK	Generic CMYK	cyan, magenta, yellow, black, alpha

componentsを確認するextension

extension NSColor {
    func printComponents() {
        print("🌈", self.colorSpace.localizedName ?? "unknown")
        print("Number of Components:", self.colorSpace.numberOfColorComponents)
        switch self.colorSpace {
        case .genericGray, .deviceGray, .genericGamma22Gray, .extendedGenericGamma22Gray:
            print("- white", self.whiteComponent)
        case .genericRGB, .deviceRGB, .sRGB, .extendedSRGB, .displayP3, .adobeRGB1998:
            print("- red", self.redComponent)
            print("- green", self.greenComponent)
            print("- blue", self.blueComponent)
            print("- hue:", self.hueComponent)
            print("- saturation:", self.saturationComponent)
            print("- brightness:", self.brightnessComponent)
        case .genericCMYK, .deviceCMYK:
            print("- cyan", self.cyanComponent)
            print("- magenta", self.magentaComponent)
            print("- yellow", self.yellowComponent)
            print("- black", self.blackComponent)
        default:
            break
        }
        print("- alpha:", self.alphaComponent)
        print()
    }
}

イニシャライザのない ColorSpace を用いるためには、.usingColorSpace(NSColorSpace)を使えば良い。

例

let deviceGray = NSColor(deviceWhite: 0.2, alpha: 1.0)
deviceGray.printComponents()
deviceGray.usingColorSpace(.sRGB)?.printComponents()
deviceGray.usingColorSpace(.deviceCMYK)?.printComponents()

let deviceRGB = NSColor(deviceRed: 0.2, green: 0.2, blue: 0.2, alpha: 1.0)
deviceRGB.printComponents()
deviceRGB.usingColorSpace(.deviceGray)?.printComponents()
deviceRGB.usingColorSpace(.deviceCMYK)?.printComponents()

let deviceCMYK = NSColor(deviceCyan: 0.2, magenta: 0.2, yellow: 0.2, black: 0.2, alpha: 1.0)
deviceCMYK.printComponents()
deviceCMYK.usingColorSpace(.deviceGray)?.printComponents()
deviceCMYK.usingColorSpace(.deviceRGB)?.printComponents()

結果

🌈 Device Gray
Number of Components: 1
- white 0.2
- alpha: 1.0

🌈 sRGB IEC61966-2.1
Number of Components: 3
- red 0.20000000298023224
- green 0.20000000298023224
- blue 0.20000000298023224
- hue: 0.0
- saturation: 0.0
- brightness: 0.20000000298023224
- alpha: 1.0

🌈 Device CMYK
Number of Components: 4
- cyan 0.8039318323135376
- magenta 0.7498183250427246
- yellow 0.7066810727119446
- black 0.37967559695243835
- alpha: 1.0

🌈 Device RGB
Number of Components: 3
- red 0.2
- green 0.2
- blue 0.2
- hue: 0.0
- saturation: 0.0
- brightness: 0.2
- alpha: 1.0

🌈 Device Gray
Number of Components: 1
- white 0.1999967396259308
- alpha: 1.0

🌈 Device CMYK
Number of Components: 4
- cyan 0.8038681149482727
- magenta 0.7498422861099243
- yellow 0.7064858078956604
- black 0.3797006607055664
- alpha: 1.0

🌈 Device CMYK
Number of Components: 4
- cyan 0.2
- magenta 0.2
- yellow 0.2
- black 0.2
- alpha: 1.0

🌈 Device Gray
Number of Components: 1
- white 0.617861270904541
- alpha: 1.0

🌈 Device RGB
Number of Components: 3
- red 0.6390809416770935
- green 0.613300621509552
- blue 0.5913392305374146
- hue: 0.07666737830114123
- saturation: 0.07470370030812351
- brightness: 0.6390809416770935
- alpha: 1.0

Gray スケール、RGB、CMYK の相互変換はよしなにやってくれているようです。（厳密には ColorSpace を正しく指定する必要があると思いますが）