当我尝试通过单击滚动视图关闭键盘时，我的应用程序崩溃

Question

我一直在尝试制作它，以便您可以点击屏幕隐藏键盘。我在这里使用的代码使应用程序崩溃。我找到了一种方法，当屏幕用于滚动而不是触摸时关闭键盘。错误如下，* *包含的位是在键盘向上触摸滚动视图时破坏应用程序的部分。        LoginViewController dismissKeyboard]：无法识别的选择器发送到实例0x7fdba2786540   *由于未捕获的异常终止应用程序＆＃39; NSInvalidArgumentException＆＃39;，原因：＆＃39; -LoginViewController dismissKeyboard]：无法识别的选择器发送到实例0x7fdba2786540＆＃39; * 第一次抛出调用堆栈：         class LoginViewController：UIViewController，UITextFieldDelegate {

@IBOutlet weak var userEmailLogin: UITextField!
@IBOutlet weak var userPasswordLogin: UITextField!
@IBOutlet weak var scroller: UIScrollView!


override func viewDidLoad() {
    super.viewDidLoad()
    scroller.contentSize.height = 500
    self.userEmailLogin.delegate = self
    self.userPasswordLogin.delegate = self



 *var tap: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: "dismissKeyboard")

    self.view.addGestureRecognizer(tap)

    func dismissKeyboard() {
        self.view.endEditing(true)
    }*



    // Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
    self.view.endEditing(true)

}
func textFieldShouldReturn(textField: UITextField) -> Bool {
    textField.resignFirstResponder()
    return true
}
@IBAction func loginButtonTapped(sender: AnyObject) {



}