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Joseph Perl
Joseph Perl
877 Points

Trouble creating a function in swift.

Hello. I am trying to create a function in swift which gives the user an alert that they haven't entered a username or password when signing up. I think there may be a problem with the way I've declared the functions parameters, but am not sure. I am using version 10.3 of Xcode. I got the code I used from a video lesson, and the code worked in the video but not on my Xcode. The is:

func displayAlert(title, message) {

let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertController.Style.alert)

alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: { (action) in
self.dismiss(animated: true, completion: nil)

    self.present(alert, animated: true, completion: nil)


@IBOutlet weak var email: UITextField!

@IBOutlet weak var password: UITextField!

@IBAction func signupOrLogin1(_ sender: Any) {

    if email.text == "" || password.text == "" {
        displayAlert("Error in form", "Please enter an email and password")


Most of the error messages are right to the right of the top line. They say: "Unnamed parameters must be written with the empty name '_'" They also say "use of undeclared type "message" and use of undeclared type "title". Another error to the right of the second line says: "Use of unresolved identifier 'message'".

Is this is syntax error in the top line? May of should used the word "string" somewhere when declaring the parameters. I also remember seeing the -> symbol sometimes next to functions, and am not sure if my version of the above code is only compatible with another version of swift or Xcode.

Thank you.

1 Answer

Kevin Tanner
Kevin Tanner
3,385 Points

Yes this is a syntax error. It looks to me like you aren't declaring the type of the parameters needed for the function. Try the code below with the types declared.

func displayAlert(title: String, message: String) {