HexStringToCUIColor.swift

extension UIColor {
   convenience init?(hexString: String) {
        let hexString = hexString.trimmingCharacters(in: .whitespacesAndNewlines)
        let scanner = Scanner(string: hexString)
        scanner.charactersToBeSkipped = CharacterSet(charactersIn: "#")
        var color: UInt64 = 0
        if scanner.scanHexInt64(&color) {
            self.init(hex: color, useOpacity: hexString.count > 7)
        } else {
            return nil
        }
    }

    convenience init(hex: UInt64, useOpacity: Bool = false) {
        let mask = UInt64(0xFF)
        let cap = !useOpacity && hex > 0xffffff ? 0xffffff : hex
        let r = cap >> (useOpacity ? 24 : 16) & mask
        let g = cap >> (useOpacity ? 16 : 8) & mask
        let b = cap >> (useOpacity ? 8 : 0) & mask
        let a = useOpacity ? cap & mask : 255
        self.init(red: CGFloat(r) / 255.0, green: CGFloat(g) / 255.0, blue: CGFloat(b) / 255.0, alpha: CGFloat(a) / 255.0)
    }

    func toHexString() -> String {
        var target = self.cgColor
        if let name = cgColor.colorSpace?.name, name != CGColorSpace.sRGB {
            let colorSpace = CGColorSpace(name: CGColorSpace.sRGB)!
            if let sRGBColor = cgColor.converted(to: colorSpace, intent: .defaultIntent, options: nil) {
                target = sRGBColor
            }
        }
        let ciColor = CIColor(cgColor: target)
        let r = lroundf(Float(ciColor.red) * 255)
        let g = lroundf(Float(ciColor.green) * 255)
        let b = lroundf(Float(ciColor.blue) * 255)
        let a = lroundf(Float(ciColor.alpha) * 255)
        if a != 255 {
            return String(format: "#%02lX%02lX%02lX%02lX", r, g, b, a)
        } else {
            return String(format: "#%02lX%02lX%02lX", r, g, b)
        }
    }
}