используйте это предупреждение, используйте правило проверки TextValidationRule.nonEmpty
import UIKit
/// A validation rule for text input.
public enum TextValidationRule {
/// Any input is valid, including an empty string.
case noRestriction
/// The input must not be empty.
case nonEmpty
/// The enitre input must match a regular expression. A matching substring is not enough.
case regularExpression(NSRegularExpression)
/// The input is valid if the predicate function returns `true`.
case predicate((String) -> Bool)
public func isValid(_ input: String) -> Bool {
switch self {
case .noRestriction:
return true
case .nonEmpty:
return !input.isEmpty
case .regularExpression(let regex):
let fullNSRange = NSRange(input.startIndex..., in: input)
return regex.rangeOfFirstMatch(in: input, options: .anchored, range: fullNSRange) == fullNSRange
case .predicate(let p):
return p(input)
}
}
}
extension UIAlertController {
public enum TextInputResult {
/// The user tapped Cancel.
case cancel
/// The user tapped the OK button. The payload is the text they entered in the text field.
case ok(String)
}
/// Creates a fully configured alert controller with one text field for text input, a Cancel and
/// and an OK button.
///
/// - Parameters:
/// - title: The title of the alert view.
/// - message: The message of the alert view.
/// - cancelButtonTitle: The title of the Cancel button.
/// - okButtonTitle: The title of the OK button.
/// - validationRule: The OK button will be disabled as long as the entered text doesn't pass
/// the validation. The default value is `.noRestriction` (any input is valid, including
/// an empty string).
/// - textFieldConfiguration: Use this to configure the text field (e.g. set placeholder text).
/// - onCompletion: Called when the user closes the alert view. The argument tells you whether
/// the user tapped the Close or the OK button (in which case this delivers the entered text).
public convenience init(title: String, message: String? = nil,
cancelButtonTitle: String, okButtonTitle: String,
validate validationRule: TextValidationRule = .noRestriction,
textFieldConfiguration: ((UITextField) -> Void)? = nil,
onCompletion: @escaping (TextInputResult) -> Void) {
self.init(title: title, message: message, preferredStyle: .alert)
/// Observes a UITextField for various events and reports them via callbacks.
/// Sets itself as the text field's delegate and target-action target.
class TextFieldObserver: NSObject, UITextFieldDelegate {
let textFieldValueChanged: (UITextField) -> Void
let textFieldShouldReturn: (UITextField) -> Bool
init(textField: UITextField, valueChange: @escaping (UITextField) -> Void, shouldReturn: @escaping (UITextField) -> Bool) {
textFieldValueChanged = valueChange
textFieldShouldReturn = shouldReturn
super.init()
textField.delegate = self
textField.addTarget(self, action: #selector(TextFieldObserver.textFieldValueChanged(sender:)), for: .editingChanged)
}
@objc func textFieldValueChanged(sender: UITextField) {
textFieldValueChanged(sender)
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
return textFieldShouldReturn(textField)
}
}
var textFieldObserver: TextFieldObserver?
// Every `UIAlertAction` handler must eventually call this
func finish(result: TextInputResult) {
// Capture the observer to keep it alive while the alert is on screen
textFieldObserver = nil
onCompletion(result)
}
let cancelAction = UIAlertAction(title: cancelButtonTitle, style: .cancel, handler: { _ in
finish(result: .cancel)
})
let okAction = UIAlertAction(title: okButtonTitle, style: .default, handler: { [unowned self] _ in
finish(result: .ok(self.textFields?.first?.text ?? ""))
})
addAction(cancelAction)
addAction(okAction)
preferredAction = okAction
addTextField { textField in
textFieldConfiguration?(textField)
textFieldObserver = TextFieldObserver(textField: textField, valueChange: { textField in
okAction.isEnabled = validationRule.isValid(textField.text ?? "")
}, shouldReturn: { textField -> Bool in
return validationRule.isValid(textField.text ?? "")
})
}
// Start with a disabled OK button if necessary
okAction.isEnabled = validationRule.isValid(textFields?.first?.text ?? "")
}
}
// Пример использования в представлении Контроллер
let alert = UIAlertController(title: "Alert", cancelButtonTitle: "Cancel", okButtonTitle: "Ok", validate: TextValidationRule.nonEmpty) { _ in
}
present(alert, animated: true, completion: nil)