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@TheCodedSelf
Last active March 31, 2024 18:00
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Disable Alert Controller button if Alert Controller text field is empty or whitespace
import UIKit
// Create an alert controller
let alertController = UIAlertController(title: "Alert", message: "Please enter text", preferredStyle: .alert)
// Create an OK Button
let okAction = UIAlertAction(title: "OK", style: .default) { (_) in
// Print "OK Tapped" to the screen when the user taps OK
print("OK Tapped")
}
// Add the OK Button to the Alert Controller
alertController.addAction(okAction)
// Add a text field to the alert controller
alertController.addTextField { (textField) in
// Observe the UITextFieldTextDidChange notification to be notified in the below block when text is changed
NotificationCenter.default.addObserver(forName: UITextField.textDidChangeNotification, object: textField, queue: OperationQueue.main, using:
{_ in
// Being in this block means that something fired the UITextFieldTextDidChange notification.
// Access the textField object from alertController.addTextField(configurationHandler:) above and get the character count of its non whitespace characters
let textCount = textField.text?.trimmingCharacters(in: .whitespacesAndNewlines).count ?? 0
let textIsNotEmpty = textCount > 0
// If the text contains non whitespace characters, enable the OK Button
okAction.isEnabled = textIsNotEmpty
})
}
@ucelme
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ucelme commented Jan 4, 2020

This happens when you have a function with wrong argument names.
Change the argument name from: .UITextFieldTextDidChange
To: UITextField.textDidChangeNotification

I changed, but anyway I get Type of expression is ambiguous without more context"

@ucelme
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ucelme commented May 21, 2020

I get error: Cannot infer contextual base in reference to member 'UITextField'

@erdogannhamdi
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thank you.

@Sigvard84
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really cool, thanks.
I would add
okAction.isEnabled = false
before add it to alertController since the TextField appears empty the first time.

I second this. The OK button will start out as enabled if this is not done. Minor line of code but pretty essential given the purpose of the whole procedure.

@asaadreh-meister
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Pretty neat. I didn't want to create a new method in an already clustered viewcontroller.

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