Displaying and handling alerts

suggest change

One Button

Swift

class ViewController: UIViewController {

    @IBAction func showAlertButtonTapped(sender: UIButton) {
        
        // create the alert
        let alert = UIAlertController(title: "My Title", message: "This is my message.", preferredStyle: UIAlertControllerStyle.Alert)
        
        // add an action (button)
        alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil))

        // show the alert
        self.presentViewController(alert, animated: true, completion: nil)
    }
}

Two Buttons

Swift

class ViewController: UIViewController {

    @IBAction func showAlertButtonTapped(sender: UIButton) {
        
        // create the alert
        let alert = UIAlertController(title: "UIAlertController", message: "Would you like to continue learning how to use iOS alerts?", preferredStyle: UIAlertControllerStyle.Alert)
        
        // add the actions (buttons)
        alert.addAction(UIAlertAction(title: "Continue", style: UIAlertActionStyle.Default, handler: nil))
        alert.addAction(UIAlertAction(title: "Cancel", style: UIAlertActionStyle.Cancel, handler: nil))
        
        // show the alert
        self.presentViewController(alert, animated: true, completion: nil)
    }
}

Three Buttons

Swift

class ViewController: UIViewController {

    @IBAction func showAlertButtonTapped(sender: UIButton) {
        
        // create the alert
        let alert = UIAlertController(title: "Notice", message: "Lauching this missile will destroy the entire universe. Is this what you intended to do?", preferredStyle: UIAlertControllerStyle.Alert)
        
        // add the actions (buttons)
        alert.addAction(UIAlertAction(title: "Remind Me Tomorrow", style: UIAlertActionStyle.Default, handler: nil))
        alert.addAction(UIAlertAction(title: "Cancel", style: UIAlertActionStyle.Cancel, handler: nil))
        alert.addAction(UIAlertAction(title: "Launch the Missile", style: UIAlertActionStyle.Destructive, handler: nil))
        
        // show the alert
        self.presentViewController(alert, animated: true, completion: nil)
    }
}

Handling Button Taps

The handler was nil in the above examples. You can replace nil with a closure to do something when the user taps a button, like the example below:

Swift

alert.addAction(UIAlertAction(title: "Launch the Missile", style: UIAlertActionStyle.Destructive, handler: { action in
    
    // do something like...
    self.launchMissile()
    
}))

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