UIAlertController in Swift

Alerts are one of the essential components of an iOS app. We use UIAlertController to get the feedback, confirmation, choose between the options, and show the warning message to the application users. There are the following components of an alert view in iOS.

Title: It represents the title of the alert shown to the user
Alert message: it is the more descriptive text that shows more details about the alert.
Alert Style: It indicates the type of alert to display.
Alert Actions: these are the actions that a user can take in response to the alert or action sheet.
Alert Textfield: it indicates the textfield to take any input from the user.

Alert Styles

Apple provides UIAlertControllerStyle Enum that contains alert styles. We can choose between two options, I.e., alert and actionsheet.

.alert: It is a normal alert displayed modally in the application.
.actionsheet: We can choose this if we need to display an actionsheet in context to the ViewController that presented it.

Example

Consider the following examples to add a different form of alerts in the app.

Adding alert to the app

import UIKit


class ViewController: UIViewController {


    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        showAlert()
    }
    
   
    func showAlert() {
        let alert = UIAlertController(title: "Logout?", message: "Are you sure you want to logout? You can login back to access your content.", preferredStyle: .alert)
        
        alert.addAction(UIAlertAction(title: "Cancel", style: UIAlertAction.Style.default, handler: { _ in
            //Cancel Action
        }))
        alert.addAction(UIAlertAction(title: "Logout",
                                      style: UIAlertAction.Style.default,
                                      handler: {(_: UIAlertAction!) in
                                        //Sign out action
        }))
       
        DispatchQueue.main.async {
            self.present(alert, animated: false, completion: nil)
        }
        
    }


}

Output

Adding actionsheet to the app

import UIKit


class ViewController: UIViewController {


    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        showAlert()
    }
    
   
    func showAlert() {
        let alert = UIAlertController(title: "Logout?", message: "Are you sure you want to logout? You can login back to access your content.", preferredStyle: .actionSheet)
        
        alert.addAction(UIAlertAction(title: "Cancel", style: UIAlertAction.Style.default, handler: { _ in
            //Cancel Action
        }))
        alert.addAction(UIAlertAction(title: "Logout",
                                      style: UIAlertAction.Style.default,
                                      handler: {(_: UIAlertAction!) in
                                        //Sign out action
        }))
       
        DispatchQueue.main.async {
            self.present(alert, animated: false, completion: nil)
        }
        
    }


}

Output

Adding alert with Destructive action

func showAlertWithDestructiveBtn() {
        let alert = UIAlertController(title: "Logout?", message: "Are you sure you want to logout? You can login back to access your content.", preferredStyle: .alert)
        
        alert.addAction(UIAlertAction(title: "Cancel", style: UIAlertAction.Style.destructive, handler: { _ in
            //Cancel Action
        }))
        alert.addAction(UIAlertAction(title: "Logout",
                                      style: UIAlertAction.Style.default,
                                      handler: {(_: UIAlertAction!) in
                                        //Sign out action
        }))
       
        DispatchQueue.main.async {
            self.present(alert, animated: false, completion: nil)
        }
        
    }

Output

Adding alert with more than two buttons

func showAlertWith2Btns() {
        let alert = UIAlertController(title: "Edit Quantity", message: "Are you sure you want to edit the quantity", preferredStyle: .alert)
        
        alert.addAction(UIAlertAction(title: "Dismiss", style: UIAlertAction.Style.destructive, handler: { _ in
            //Cancel Action
        }))
        alert.addAction(UIAlertAction(title: "Add 1 item",
                                      style: UIAlertAction.Style.default,
                                      handler: {(_: UIAlertAction!) in
                                        //Add an item
        }))


       alert.addAction(UIAlertAction(title: "Remove 1 item",
                                     style: UIAlertAction.Style.default,
                                     handler: {(_: UIAlertAction!) in
                                       //Remove an item
       }))
        
        DispatchQueue.main.async {
            self.present(alert, animated: false, completion: nil)
        }
        
    }

Output

Adding alert with TextField

func showAlertWithTF() {
        let alertController = UIAlertController(title: "Add new Items", message: nil, preferredStyle: .alert)
        let addAction = UIAlertAction(title: "Add", style: .default) { (_) in
            if let txtField = alertController.textFields?.first, let text = txtField.text {
                // operations
                
            }
        }
        let cancelAction = UIAlertAction(title: "Cancel", style: .cancel) { (_) in }
        alertController.addTextField { (textField) in
            textField.placeholder = "Item name"
        }
        alertController.addAction(addAction)
        alertController.addAction(cancelAction)
        DispatchQueue.main.async {
            self.present(alertController, animated: true, completion: nil)
        }
        
    }

Output