Hex to UIColor (Swift2.3 xcode 7.3.1)

func colorWithHexString (hex:String) -> UIColor {
    var cString:String = hex.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet()).uppercaseString

    if (cString.hasPrefix("#")) {
        cString = (cString as NSString).substringFromIndex(1)
    }

    if (cString.characters.count != 6) {
        return UIColor.grayColor()
    }

    let rString = (cString as NSString).substringToIndex(2)
    let gString = ((cString as NSString).substringFromIndex(2) as NSString).substringToIndex(2)
    let bString = ((cString as NSString).substringFromIndex(4) as NSString).substringToIndex(2)

    var r:CUnsignedInt = 0, g:CUnsignedInt = 0, b:CUnsignedInt = 0;
    NSScanner(string: rString).scanHexInt(&r)
    NSScanner(string: gString).scanHexInt(&g)
    NSScanner(string: bString).scanHexInt(&b)


    return UIColor(red: CGFloat(r) / 255.0, green: CGFloat(g) / 255.0, blue: CGFloat(b) / 255.0, alpha: CGFloat(1))
}