NSImage class extension initializer for quickly creating swatches of NSColors.

NSImage Color Swatch.swift

public extension NSImage {
    /// Initializes and returns a new color swatch image.
    /// - Parameters:
    ///   - color: The fill color of the image.
    ///   - size: The width and height of the image.
    convenience init(color: NSColor, size: NSSize) throws {
        self.init(size: size)
        
        guard let ciColor = CIColor(color: color) else {
            assertionFailure("Could not create CIColor from NSColor")
            return
        }

        let rect = CGRect(origin: .zero, size: size);
        let ciImage = CIImage(color: ciColor).cropped(to: rect)
        let bitmapRep = NSBitmapImageRep(ciImage: ciImage)
        
        NSGraphicsContext.saveGraphicsState()
        NSGraphicsContext.current = NSGraphicsContext(bitmapImageRep: bitmapRep)
        ciImage.draw(in: rect, from: .zero, operation: .copy, fraction: 1.0)
        NSGraphicsContext.restoreGraphicsState()
        
        self.addRepresentation(bitmapRep)
    }
}