How to add UIColor extensions in swift

CustomColors+UIColor.swift

import Foundation
import UIKit

extension UIColor{
    //create a class function with the name of the custom color
    class func lazcolor() -> UIColor {
        return UIColor(red: 190.0/255.0, green: 190.0/255.0, blue: 190.0/255.0, alpha: 1.0)
    }
    
    class func grayScaleColor(grayScale : CGFloat) -> UIColor {
        return UIColor(red: grayScale/255.0, green: grayScale/255.0, blue: grayScale/255.0, alpha: 1.0)
    }



}