How to make the cancel button in alert cancel the action? - swift

Question

I made an alert as you can see, but the app adds the item, no matter if I'm clicking the "NO" button og the "Yes, I'm sure" button when the alert pops up.
My goal is to make the "NO" action, cancel the action so the input won't be added anyway. Can you tell me how to?
import UIKit
class SecondViewController: UIViewController, UITextFieldDelegate {
#IBOutlet weak var input: UITextField!
#IBAction func addItem(_ sender: Any)
{
createAlert(title: "That's a good grail!", message: "Are you sure you want to add this grail?")
if (input.text != "")
{
list.append(input.text!)
input.text = ""
}
}
override func viewDidLoad()
{
super.viewDidLoad()
self.input.delegate = self
}
//HIDE KEYBOARD:
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
self.view.endEditing(true)
}
//PRESSES RETURN KEY:
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
input.resignFirstResponder()
return true
}
func createAlert (title:String, message:String)
{
let alertController = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
//CREATING OK BUTTON
let OKAction = UIAlertAction(title: "Yes, I'm sure!", style: .default) { (action:UIAlertAction!) in
// Code in this block will trigger when OK button tapped.
print("Ok button tapped");
}
alertController.addAction(OKAction)
// Create Cancel button
let cancelAction = UIAlertAction(title: "No!", style: .cancel) { (action:UIAlertAction!) in
print("Cancel button tapped");
}
alertController.addAction(cancelAction)
// Present Dialog message
self.present(alertController, animated: true, completion:nil)
}
}
EDIT:
The code looks like this now, thanks:
import UIKit
class SecondViewController: UIViewController, UITextFieldDelegate {
#IBOutlet weak var input: UITextField!
#IBAction func addItem(_ sender: Any)
{
createAlert(title: "That's a good grail!", message: "Are you sure you want to add this grail?")
}
override func viewDidLoad()
{
super.viewDidLoad()
self.input.delegate = self
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
//HIDE KEYBOARD:
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
self.view.endEditing(true)
}
//PRESSES RETURN KEY:
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
input.resignFirstResponder()
return true
}
func createAlert (title:String, message:String)
{
let alertController = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
//CREATING OK BUTTON
let OKAction = UIAlertAction(title: "Yes, I'm sure!", style: .default) { (action:UIAlertAction!) in
// Code in this block will trigger when OK button tapped.
print("Ok button tapped");
if (self.self.input.text != "")
{
list.append(self.input.text!)
self.input.text = ""
}
}
alertController.addAction(OKAction)
// Create Cancel button
let cancelAction = UIAlertAction(title: "No!", style: .cancel) { (action:UIAlertAction!) in
print("Cancel button tapped");
}
alertController.addAction(cancelAction)
// Present Dialog message
self.present(alertController, animated: true, completion:nil)
}
}

Answer 1

simply just put the code for adding the item to the OK closure:
class SecondViewController: UIViewController, UITextFieldDelegate {
#IBOutlet weak var input: UITextField!
#IBAction func addItem(_ sender: Any)
{
createAlert(title: "That's a good grail!", message: "Are you sure you want to add this grail?")
}
override func viewDidLoad()
{
super.viewDidLoad()
self.input.delegate = self
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
//HIDE KEYBOARD:
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
self.view.endEditing(true)
}
//PRESSES RETURN KEY:
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
input.resignFirstResponder()
return true
}
func createAlert (title:String, message:String)
{
let alertController = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
//CREATING OK BUTTON
let OKAction = UIAlertAction(title: "Yes, I'm sure!", style: .default) { (action:UIAlertAction!) in
// Code in this block will trigger when OK button tapped.
if (input.text != "")
{
list.append(input.text!)
input.text = ""
}
print("Ok button tapped");
}
alertController.addAction(OKAction)
// Create Cancel button
let cancelAction = UIAlertAction(title: "No!", style: .cancel) { (action:UIAlertAction!) in
print("Cancel button tapped");
}
alertController.addAction(cancelAction)
// Present Dialog message
self.present(alertController, animated: true, completion:nil)
}
}

Answer 2

You're adding the input.text anyway in your addItem(_ :) method after you show your UIAlertController.
So if you want to avoid the input.text is added always and only when the OK button is tapped you should include in the closure for the action when you created it and remove it after the presentation of the UIAlertController
let OKAction = UIAlertAction(title: "Yes, I'm sure!", style: .default) { [weak self] _ in
guard let selfStrong = self else {
return
}
// Code in this block will trigger when OK button tapped.
if (selfStrong.input.text != "") {
selfStrong.list.append(input.text!)
selfStrong.input.text = ""
}
}
For the cancel button, you don't need any action closure unless you want to do something when the cancel button is tapped too.
I hope this helps you.

Answer 3

You are not appending the item on click of "Yes, I'm sure" button. Remove the below code inside #IBAction func addItem(_ sender: Any) method and put it inside OKAction handler block.
if (input.text != "")
{
list.append(input.text!)
input.text = ""
}
Do like this:
#IBAction func addItem(_ sender: Any)
{
createAlert(title: "That's a good grail!", message: "Are you sure you want to add this grail?")
}
Inside method: func createAlert (title:String, message:String) (put append code here)
let OKAction = UIAlertAction(title: "Yes, I'm sure!", style: .default) { (action:UIAlertAction!) in
// Code in this block will trigger when OK button tapped.
print("Ok button tapped");
if (input.text != "")
{
list.append(input.text!)
input.text = ""
}
}