Tinting a grayscale NSImage (or CIImage)

Question

I have a grayscale image which I want to use for drawing Cocoa controls. The image has various levels of gray. Where it is darkest, I want it to draw a specified tint color dark

Answer 1

Swift version in form of Extension :

extension NSImage {
    func tintedImageWithColor(color:NSColor) -> NSImage {
        let size        = self.size
        let imageBounds = NSMakeRect(0, 0, size.width, size.height)
        let copiedImage = self.copy() as! NSImage

        copiedImage.lockFocus()
        color.set()
        NSRectFillUsingOperation(imageBounds, .CompositeSourceIn)
        copiedImage.unlockFocus()

        return copiedImage
    }
}