Save NSColor components to file - cocoa

Question

I am trying to save an instance of NSColor to a file like this:
writeF(node.lineColour.hueComponent)
writeF(node.lineColour.saturationComponent)
writeF(node.lineColour.brightnessComponent)
writeF(node.lineColour.alphaComponent)
where the write function is:
func writeF(var val: CGFloat) -> Bool {
let nsd = NSData(bytes: &val, length: sizeof(CGFloat))
let rv = oStream!.write(UnsafePointer(nsd.bytes), maxLength: sizeof(CGFloat))
return rv > 0
}
And "node.lineColour" is just NSColor.blueColor(). It all compiles OK, but gives a run-time message at the first "writeF" line:
2015-10-01 07:57:43.871 canl[77917:8371660] An uncaught exception was raised
2015-10-01 07:57:43.871 canl[77917:8371660] *** -hueComponent not valid for the NSColor NSCalibratedWhiteColorSpace 0 1; need to first convert colorspace.
Apple documentation on color spaces is very esoteric (if you already understand it then it's a fine reference, but if not then... good luck). Why is the above code wrong? Should be able to at least retrieve the color components (CGFloat).

Answer 1

After swimming through the available documentation and trying different things, I found this to work:
let aColor = node.lineColor.colorUsingColorSpaceName(NSCalibratedRGBColorSpace)
if let culoare = aColor {
writeF(culoare.redComponent)
writeF(culoare.greenComponent)
writeF(culoare.blueComponent)
writeF(culoare.alphaComponent)
}
It also works for getting the hue, saturation, and brightness components, but I think I will go with RGB.