Returns a contrasting NSColor for this NSColor. Useful for putting text on a plain color background or the like...

NSColor+contrastingTextColor.swift

extension NSColor {
   private struct ColorComponents {
      var r: CGFloat = 0.0
      var g: CGFloat = 0.0
      var b: CGFloat = 0.0
      var a: CGFloat = 0.0
   }

   private func components() -> ColorComponents {
      var result = ColorComponents()
      self.getRed(&result.r, green: &result.g, blue: &result.b, alpha: &result.a)
      return result
   }

   func contrastingTextColor() -> NSColor {
      if self == NSColor.clear {
         return .black
      }

      guard let c1 = self.usingColorSpace(.deviceRGB) else {
         return .black
      }

      let rgbColor = c1.components()

      // Counting the perceptive luminance - human eye favors green color...
      let avgGray: CGFloat = 1 - (0.299 * rgbColor.r + 0.587 * rgbColor.g + 0.114 * rgbColor.b)
      return avgGray > 0.5 ? .white : .black
   }
}