UIColor16进制颜色

例子: 用这个16色的做的蒙版效果,附带透明度20%的需求
//  mengbanView.backgroundColor = UIColor.ZNColor_16RGB_alpha(hex: "#000000", alpha: 0.2)

import UIKit

extension UIColor {
   static func ZNColor_16RGB (hex:String) -> UIColor {
        var cString:String = hex.trimmingCharacters(in: NSCharacterSet.whitespacesAndNewlines)
        if (cString.hasPrefix("#")) {
            cString = (cString as NSString).substring(from: 1)
        }
        let rString = (cString as NSString).substring(to: 2)
        let gString = ((cString as NSString).substring(from: 2) as NSString).substring(to: 2)
        let bString = ((cString as NSString).substring(from: 4) as NSString).substring(to: 2)
        var r:CUnsignedInt = 0, g:CUnsignedInt = 0, b:CUnsignedInt = 0;
        Scanner(string: rString).scanHexInt32(&r)
        Scanner(string: gString).scanHexInt32(&g)
        Scanner(string: bString).scanHexInt32(&b)
        return UIColor(red: CGFloat(r) / 255.0, green: CGFloat(g) / 255.0, blue: CGFloat(b) / 255.0, alpha: CGFloat(1))
    }
    
   static func ZNColor_16RGB_alpha (hex:String, alpha:CGFloat) -> UIColor {
        var cString:String = hex.trimmingCharacters(in: NSCharacterSet.whitespacesAndNewlines)
        if (cString.hasPrefix("#")) {
            cString = (cString as NSString).substring(from: 1)
        }
        let rString = (cString as NSString).substring(to: 2)
        let gString = ((cString as NSString).substring(from: 2) as NSString).substring(to: 2)
        let bString = ((cString as NSString).substring(from: 4) as NSString).substring(to: 2)
        var r:CUnsignedInt = 0, g:CUnsignedInt = 0, b:CUnsignedInt = 0;
        Scanner(string: rString).scanHexInt32(&r)
        Scanner(string: gString).scanHexInt32(&g)
        Scanner(string: bString).scanHexInt32(&b)
        return UIColor(red: CGFloat(r) / 255.0, green: CGFloat(g) / 255.0, blue: CGFloat(b) / 255.0, alpha: alpha)
    }
}