Add Hyphen in UITextfield (auto add hyphen and parentheses) - in Swift2

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

{

    sendButton.enabled = true

    let newString = (textField.text! as NSString).stringByReplacingCharactersInRange(range, withString: string)

    let components = newString.componentsSeparatedByCharactersInSet(NSCharacterSet.decimalDigitCharacterSet().invertedSet)

    let decimalString : String = components.joinWithSeparator("")

    let length = decimalString.characters.count

    let decimalStr

    let decimalStr = decimalString as NSString

    let hasLeadingOne = length > 0 && decimalStr.characterAtIndex(0)== (1 as unichar)

    if length == 0 || (length > 10 && !hasLeadingOne) || length > 11

    {

        let newLength = (textField.text! as NSString).length + (string as NSString).length - range.length as Int return (newLength > 10) ? false : true

    }

    var index = 0 as Int let formattedString = NSMutableString()

    if hasLeadingOne

    { formattedString.appendString("1 ") index += 1

    }

    if (length - index) > 3

    {

        let areaCode = decimalStr.substringWithRange(NSMakeRange(index, 3))

        formattedString.appendFormat("(%@)", areaCode) index += 3

    }

    if length - index > 3

    {

        let prefix = decimalStr.substringWithRange(NSMakeRange(index, 3))

        formattedString.appendFormat("%@-", prefix) index += 3

    }

    let remainder = decimalStr.substringFromIndex(index) formattedString.appendString(remainder)

    textField.text = formattedString as String

    return false

}




By using this you can achieve both restrict phone number to 10 digit and format it as per US format.