iOS Swift4.0 Return Value : I am new to the swift programming so have a question on the return value. 

Suppose I have this code block: 

    @IBAction func verifyItemPressed() {
        if pinTextField.text?.isEmpty ?? true {
            UIAlertController.showAlertWith(title: "Test", message: "Empty entry!!")
            return
        }

In this case, what return value I can expect here. Since, what I know is that it should return either 0 or 1 and true or false (if I have defined bool)

Thanks in advance