How to disable UIAlertController Buttons?

I've discovered .isEnabled for the buttons, so that's a step forward. I'm guessing now that they might perhaps be enabled within some textfield delegate method.

Here is a template for this (example: ask for a city name ; Search button enabled if name non empty).

Alert is called when tapping a button: here is the IBAction:

    var alert : UIAlertController?          // Declared in the class

    @IBAction func testAlert(_ sender: Any) {
        //1. Create the alert controller.
        alert = UIAlertController(title: "Search city", message: "City name ", preferredStyle: .alert)
   
        //2. Add the text field.
        alert?.addTextField(configurationHandler: { (textField) -> Void in
            textField.placeholder = ""
            textField.keyboardType = UIKeyboardType.emailAddress // To have @ ; or any other keyboard type you wish
            textField.addTarget(self, action: #selector(self.alertTextFieldDidChange(_:)), for: UIControl.Event.editingChanged)     // Action when we type in textField
        })
   
        //3. Grab the value from the text field. At the end, when hitting search
        let yesAction = UIAlertAction(title: "Search", style: .default, handler: { (action) -> Void in
            let textField = self.alert?.textFields![0]
            if textField?.text! == "" {     // When we have hit Search, if enabled
                print("empty")
            } else {
                print("not empty", textField?.text! ?? "")
            }
        })
        yesAction.isEnabled = false
        alert?.addAction(yesAction)   // Disabled on alert creation
   
        // 4. Present the alert.
        self.present(alert!, animated: true, completion: nil)
    }

// Test if textField empty ; note that it was created disabled
    @objc func alertTextFieldDidChange(_ sender: UITextField) {
        alert?.actions[0].isEnabled = sender.text!.count > 0
    }

Hope that helps.

Awesome! Thanks, Claude, that's been a great help.

Hi, Claude, I have a question about #selector. I see that it specifically wants an objc method, but I've been playing around and it seems to call methods such as "TextFieldShouldEndEditing", which are not bridged to @objc, without issue. I'm assuming that is probably not that case and it really shouldn't be done?

These are 2 different things :

TextFieldShouldEndEditing is a delegate function you defined. It is linked "naturally" by compiler.

In #selector, you have a func that must be found dynamically (at run time). You have to use a dynamic dispatch.

@objc forces to include in a dynamic dispatch table.

To test where you need, change the setting of @objc inference to false and compile:

Read here to see how to set this:

https://stackoverflow.com/questions/44379348/the-use-of-swift-3-objc-inference-in-swift-4-mode-is-deprecated

If you introduce new methods or variables to a Swift class, marking them as

@objc

Selectors

button.addTarget(self, action:#selector(didPressButton), for:.touchUpInside)

- Why would I not mark everything

@objc

There are negatives that come with marking something as

@objc

• Increased application binary size
• No function overloading

Thanks, Claude. Someone else introduced me to a way to acheive it by using notification center. Do you know if there are advantages to one over the other? I guess it all depends on the context.
https://gist.github.com/TheCodedSelf/c4f3984dd9fcc015b3ab2f9f60f8ad51?fbclid=IwAR2d9rHhOxLcwemRvLMl-x4wfwwoywjqgHFJ3NQGb7aCqBzufpYCTlEWvy8

I know this post is a little dated but it's exactly what I needed. I've been able to implement however I can't seem to enable the alert button (or disable) in the objc function. It just doesn't do anything;

    @objc func alertTextFieldDidChange(_ sender: UITextField) {
        print("In the alert did change")
        print("Should Save be enabled?  \(sender.text!.count > 0)")
        print("Button title is \(alertController?.actions[0].title)")
        alertController?.actions[0].isEnabled = sender.text!.count > 0
    }

I've confirmed that the notification for text changed is received by function and confirmed that the sender,text.count > 0 is true (or false) so it should be enabling but it's not. I even tried just enabling the button automatically whenever any textChange event received (alertController?.actions[0].isEnabled = true) but that didn't work either. I am using XCode 14.2. I found other examples of people doing it this way as well however they were just using a single action button. Any idea why this button isn't enabling?