Can a UIAlertAction trigger a function?

Question

Is it possible to connect a function to an UIAlertAction?

So after a user clicks the OK button it performs an action? Isn't this what the handler parameter does?

let alert: UIAlertController = UIAlertController(title: "Email already registered", message: "Please enter a different email", preferredStyle: .alert)
let okButton = UIAlertAction(title: "OK", style: .default, handler: backToLogin())

alert.addAction(okButton)
self.presentViewController(alert, animated: true, completion: nil)

...

func backToLogin() {
    self.performSegueWithIdentifier("toLoginPage", sender: self)
}

Look your code format. It's terrible – Long Pham Jul 24 '15 at 03:24 — Long Pham, Jul 24 '15 at 03:24

score 4 · Accepted Answer · answered Jul 24 '15 at 04:04

You can use a function as the handler, but it needs to have the correct type. Also you must not call it when you pass it as an argument, i.e., instead of handler: backToLogin() (which would set the return value of backToLogin as the handler) you would have handler: backToLogin without the ().

The following should work:

func backToLogin(alertAction: UIAlertAction) {
    self.performSegueWithIdentifier("toLoginPage", sender: self)
}
let okButton = UIAlertAction(title: "OK", style: .Default, handler: backToLogin)

But having to change backToLogin might defeat the purpose, so you could just use a closure:

let okButton = UIAlertAction(title: "OK", style: .Default) { _ in
    self.backToLogin()
}

Worked perfect, thanks! I'm looking into closures more now...thanks again! — , Jul 24 '15 at 04:56

score 0 · Answer 2 · edited May 23 '17 at 11:53

0

You need to enter the handler

let okButton = UIAlertAction(title: "OK", style: .Default, handler: {

(UIAlertAction) in

self.backToLogin()

})

}

See this answer for more info: Writing handler for UIAlertAction

edited May 23 '17 at 11:53

Community

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1

answered Jul 24 '15 at 03:25

Fred Faust

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Can a UIAlertAction trigger a function?

2 Answers2