swift4 16进制转RGB

withDrawBtn.backgroundColor = UIColor.colorWithHexString(Color_Value: "#e6761c", alpha: 1.0)

 

 class   func colorWithHexString (Color_Value:NSString, alpha: CGFloat)->UIColor{
        var  Str :NSString = Color_Value
        if Color_Value.hasPrefix("#"){
            Str=(Color_Value as NSString).substring(from: 1) as NSString
        }
        let redStr = (Str as NSString ).substring(to: 2)
        let greenStr = ((Str as NSString).substring(from: 2) as NSString).substring(to: 2)
        let blueStr = ((Str as NSString).substring(from: 4) as NSString).substring(to: 2)
        var r:CUnsignedInt = 0, g:CUnsignedInt = 0, b:CUnsignedInt = 0;
        Scanner(string:redStr).scanHexInt32(&r)
        Scanner(string: greenStr).scanHexInt32(&g)
        Scanner(string: blueStr).scanHexInt32(&b)
        return UIColor(red: CGFloat(r)/255.0, green: CGFloat(g)/255.0, blue: CGFloat(b)/255.0, alpha: alpha)
    }