UIColor: Is grayscale value a property?

Question

https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIColor_Class/#//apple_ref/occ/clm/UIColor/blackColor

Creating a UIColor with Preset Component Values

+ blackColor

Returns a color object whose grayscale value is 0.0 and whose alpha value is 1.0.

Is there a method to retrieve a color objects "grayscale value"?

Answer 1

You can use the getWhite(_:alpha:) method on UIColor to effectively get the grayscale values.

Playground example:

import UIKit

let piColor = UIColor(red: 0.31, green: 0.41, blue: 0.59, alpha: 1.0)
var grayscale: CGFloat = 0
var alpha: CGFloat = 0

if piColor.getWhite(&grayscale, alpha: &alpha) {
    grayscale
    let grayscaleColor = UIColor(white: grayscale, alpha: alpha)
}