Swift-十六进制转UIColor

extension UIColor{

    

    class func colorWithHexString(hex:String,alpha:CGFloat) -> UIColor {

        

        var cString = hex.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines).uppercased()

        

        if cString.hasPrefix("#") {

            let index = cString.index(after: cString.startIndex)

            cString = cString.substring(from: index)

        }

        if cString.characters.count != 6 {

            return UIColor.black

        }

        

        let rRange = cString.startIndex ..< cString.index(cString.startIndex, offsetBy: 2)

        let rString = cString.substring(with: rRange)

        

        print(rString);

        

        let gRange = cString.index(cString.startIndex, offsetBy: 2) ..< cString.index(cString.startIndex, offsetBy: 4)

        let gString = cString.substring(with: gRange)

        

        print(gString);

        

        let bRange = cString.index(cString.startIndex, offsetBy: 4) ..< cString.index(cString.startIndex, offsetBy: 6)

        let bString = cString.substring(with: bRange)

        

        print(bString);

        

        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)

        

    }

    

}