IOS alert dialog example

1. Add a button to the storyboard from the object library.

2. Ctrl and drag the button to the ViewController, select action and give it a name helloWorld.

3. Add the following in the IBAction function.

// Create the alert dialog
let alertDialog = UIAlertController(title: "Hello World",
                                    message: "Congrats! You've created your first alert in ios app!",
                                    preferredStyle: .alert)

// The button on the alert dialog
let action = UIAlertAction(title: "Fantastic", style: .default, handler: nil)

// Add the button to the alert dialog
alertDialog.addAction(action)

// Show the alert dialog
present(alertDialog, animated: true, completion: nil)

4. Command + R, to run the app.

5. The ViewController.swift should look like this.

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    @IBAction func helloWorld(_ sender: UIButton) {
        // Create the alert dialog
        let alertDialog = UIAlertController(title: "Hello World",
                                            message: "Congrats! You've created your first alert in ios app!",
                                            preferredStyle: .alert)
        
        // The button on the alert dialog
        let action = UIAlertAction(title: "Fantastic", style: .default, handler: nil)
        
        // Add the button to the alert dialog
        alertDialog.addAction(action)
        
        // Show the alert dialog
        present(alertDialog, animated: true, completion: nil)
    }
    
}

Complete example in Github