How to prevent special characters in UITextField of UIAlertViewController?

Question

I have UIAlertViewController as shown below image.

here's my code :

let alertController = UIAlertController(title: alertTitle.security, message: "", preferredStyle: UIAlertController.Style.alert)
    alertController.addTextField { (textField : UITextField!) -> Void in
        textField.placeholder = placeholder.security
        textField.tintColor = .black
        textField.isSecureTextEntry = true
    }

I want to prevent some special characters to insert into UITextField.

Answer : https://codereview.stackexchange.com/questions/187441/prevent-a-uitextfield-from-being-input-with-aphabetic-characters — dahiya_boy, Apr 17 '19 at 10:23

score 2 · Answer 1 · answered Apr 17 '19 at 10:32

2

You Have to assign the textfield the delegate

textField.delegate = self

then check check if special character or not

 extension ViewController: UITextFieldDelegate {
        public func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
            if textField.isFirstResponder {
                let validString = CharacterSet(charactersIn: "!@#$%^&*()_+{}[]|\"<>,.~`/:;?-=\\¥'£•¢")


                if let range = string.rangeOfCharacter(from: validString) {
                    return false
                }
            }
            return true
        }

    }

answered Apr 17 '19 at 10:32

Razi Tiwana

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@UdayBabariya whats not working?, maybe you forgot to add `textField.delegate = self `. – Razi Tiwana Apr 17 '19 at 14:05
-UiAlertViewController do not use the delegate methods of its base ViewController. – Uday Babariya Apr 17 '19 at 14:52
This should only happen if you are subclassing the `UIAlertViewController ` in that case just more your `shouldChangeCharactersIn ` to that `UIAlertViewController` – Razi Tiwana Apr 17 '19 at 15:17
Can you add all the relevant code in the question, what exactly are your doing? – Razi Tiwana Apr 18 '19 at 04:32

score 0 · Answer 2 · answered Apr 17 '19 at 10:24

Hope this help :

let alertController = UIAlertController(title: alertTitle.security, message: "", preferredStyle: UIAlertController.Style.alert)
    alertController.addTextField { (textField : UITextField!) -> Void in
        textField.placeholder = placeholder.security
        textField.tintColor = .black
        textField.isSecureTextEntry = true
        textField.delegate = self // new
    }


func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if string == "(special chracter)" {
        return false
    }
    return true
}

How to prevent special characters in UITextField of UIAlertViewController?

2 Answers2