iOS UIAlertController Displaying and handling alerts
Example
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()
}))
Notes
- Multiple buttons do not necessarily need to use different
UIAlertActionStyletypes. They could all be.Default. - For more than three buttons consider using an Action Sheet. The setup is very similar. Here is an example.
