在 Swift 中格式化电话号码

我正在格式化我的文本文件，一旦用户开始将电话号码输入到这个格式类型0 (555) 444 66 77，它工作正常，但一旦我从服务器上获得号码，我就会得到这个05554446677，所以请告诉我，一旦我从服务器上获得号码，我如何以同样的格式编辑它？

我的代码一旦开始输入:

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {

    if textField == phoneNumberTextField{
        var newString = (textField.text as NSString).stringByReplacingCharactersInRange(range, withString: string)
        var components = newString.componentsSeparatedByCharactersInSet(NSCharacterSet.decimalDigitCharacterSet().invertedSet)

        var decimalString = "".join(components) as NSString
        var length = decimalString.length
        var hasLeadingOne = length > 0 && decimalString.characterAtIndex(0) == (1 as unichar)

        if length == 0 || (length > 11 && !hasLeadingOne) || length > 12{
            var newLength = (textField.text as NSString).length + (string as NSString).length - range.length as Int

            return (newLength > 11) ? false : true
        }
        var index = 0 as Int
        var formattedString = NSMutableString()

        if hasLeadingOne{
            formattedString.appendString("1 ")
            index += 1
        }

        if (length - index) > 1{
            var zeroNumber = decimalString.substringWithRange(NSMakeRange(index, 1))
            formattedString.appendFormat("%@ ", zeroNumber)
            index += 1
        }
        if (length - index) > 3{
            var areaCode = decimalString.substringWithRange(NSMakeRange(index, 3))
            formattedString.appendFormat("(%@) ", areaCode)
            index += 3
        }
        if (length - index) > 3{
            var prefix = decimalString.substringWithRange(NSMakeRange(index, 3))
            formattedString.appendFormat("%@ ", prefix)
            index += 3
        }
        if (length - index) > 3{
            var prefix = decimalString.substringWithRange(NSMakeRange(index, 2))
            formattedString.appendFormat("%@ ", prefix)
            index += 2
        }

        var remainder = decimalString.substringFromIndex(index)
        formattedString.appendString(remainder)
        textField.text = formattedString as String
        return false
    }else{
        return true
    }
}