如何验证 UIAlertController 中的文本字段？

【问题标题】：How do I validate TextFields in an UIAlertController?如何验证 UIAlertController 中的文本字段？
【发布时间】：2015-06-02 12:59:38
【问题描述】：

谁能告诉我如何在UIAlertController 中验证UITextFields？

我需要它来防止用户点击“保存”，除非两个字段都输入。

到目前为止，这是我的代码：

@IBAction func btnStart(sender: AnyObject) {
    var alert = UIAlertController(title: "New user",
        message: "Add a new user",
        preferredStyle: .Alert)

    let saveAction = UIAlertAction(title: "Save",
        style: .Default) { (action: UIAlertAction!) -> Void in

            self.textFieldName = alert.textFields![0] as UITextField
            self.textFieldEmail = alert.textFields![1] as UITextField
            self.saveUser(self.textFieldName.text, email: self.textFieldEmail.text)
            self.tableView.reloadData()
    }

    saveAction.enabled = false

    let cancelAction = UIAlertAction(title: "Cancel",
        style: .Default) { (action: UIAlertAction!) -> Void in
    }

    alert.addTextFieldWithConfigurationHandler {
        (textFieldName: UITextField!) in
        textFieldName.placeholder = "Enter full name"
    }

    alert.addTextFieldWithConfigurationHandler {
        (textFieldEmail: UITextField!) in
        textFieldEmail.placeholder = "Enter valid email adress"
        textFieldEmail.keyboardType = .EmailAddress

    }
    alert.addAction(saveAction)
    alert.addAction(cancelAction)

    presentViewController(alert,
        animated: true,
        completion: nil)
}

这是我验证电子邮件字段的函数：

func isValidEmail(testStr:String) -> Bool {
    let emailRegEx = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"

    if let emailTest = NSPredicate(format:"SELF MATCHES %@", emailRegEx) {
        return emailTest.evaluateWithObject(testStr)
    }
    return false
}

【问题讨论】：

标签： ios swift uitextfield uialertview


【解决方案1】：

这可以通过扩展UIAlertViewController来完成：

extension UIAlertController {

    func isValidEmail(_ email: String) -> Bool {
        return email.characters.count > 0 && NSPredicate(format: "self matches %@", "[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,64}").evaluate(with: email)
    }

    func isValidPassword(_ password: String) -> Bool {
        return password.characters.count > 4 && password.rangeOfCharacter(from: .whitespacesAndNewlines) == nil
    }

    func textDidChangeInLoginAlert() {
        if let email = textFields?[0].text,
            let password = textFields?[1].text,
            let action = actions.last {
            action.isEnabled = isValidEmail(email) && isValidPassword(password)
        }
    }
}

// ViewController
override func viewDidLoad() {
    super.viewDidLoad()

    let alert = UIAlertController(title: "Please Log In", message: nil, preferredStyle: .alert)

    alert.addTextField {
        $0.placeholder = "Email"
        $0.addTarget(alert, action: #selector(alert.textDidChangeInLoginAlert), for: .editingChanged)
    }

    alert.addTextField {
        $0.placeholder = "Password"
        $0.isSecureTextEntry = true
        $0.addTarget(alert, action: #selector(alert. textDidChangeInLoginAlert), for: .editingChanged)
    }

    alert.addAction(UIAlertAction(title: "Cancel", style: .cancel))

    let loginAction = UIAlertAction(title: "Submit", style: .default) { [unowned self] _ in
        guard let email = alert.textFields?[0].text,
            let password = alert.textFields?[1].text
            else { return } // Should never happen

        // Perform login action
    }

    loginAction.isEnabled = false
    alert.addAction(loginAction)
    present(alert, animated: true)
}

【讨论】：

  • 很好的答案，唯一需要改变的是在textDidChangeInLoginAlert() 函数之前添加@objc
【解决方案2】：

最优雅的方式是使用

NotificationCenter.default.addObserver(forName: NSNotification.Name.UITextFieldTextDidChange...

Swift 3.0 示例

let alert = UIAlertController(title: nil, message: nil, preferredStyle: .alert)
    alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
    let saveAction = UIAlertAction(title:"Save", style: .destructive, handler: { (action) -> Void in

    })
    alert.addAction(saveAction)
    alert.addTextField(configurationHandler: { (textField) in
        textField.placeholder = "Enter something"
        NotificationCenter.default.addObserver(forName: NSNotification.Name.UITextFieldTextDidChange, object: textField, queue: OperationQueue.main) { (notification) in
            saveAction.isEnabled = textField.text!.length > 0
        }
    })
    present(alert, animated: true, completion: nil)

【讨论】：

  • 您是否需要在某个时候移除观察者，或者尽管有观察者，但文本字段会正常释放吗？
  • 如果您的应用面向 iOS 9.0 及更高版本或 macOS 10.11 及更高版本，则无需在其 dealloc 方法中取消注册观察者。 （耶！）在此处查看文档：developer.apple.com/documentation/foundation/notificationcenter/…
【解决方案3】：

Swift 4.0 示例

这是基于 Mihael Isaev 的回答。我不得不对其进行一些更改以使“保存”按钮不立即处于活动状态。我尝试使用和不使用占位符文本。最后，不得不专门停用保存开始。就我而言，我选择使用警报标题而不是占位符文本。但是，无论哪种方式，它的工作原理都是一样的。

let alert = UIAlertController(title: "Enter Username", message: nil, preferredStyle: .alert)

alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: { (action) -> Void in}))
let saveAction = UIAlertAction(title:"Save", style: .destructive, handler: { (action) -> Void in
})
alert.addAction(saveAction)
alert.addTextField(configurationHandler: { (textField) in
    textField.text = ""
    saveAction.isEnabled = false
    NotificationCenter.default.addObserver(forName: NSNotification.Name.UITextFieldTextDidChange, object: textField, queue: OperationQueue.main) { (notification) in
        saveAction.isEnabled = textField.text!.length > 0
    }
})
self.present(alert, animated: true, completion: nil)

【讨论】：

  • 对于 Swift 5，只需从 forName 参数中删除 NSNotification.Name.。我还建议将 textField 和 saveAction 都传递为 weak 以防止循环
【解决方案4】：

对于 Swift 4.2 (NSNotification.Name.UITextFieldTextDidChange) 更新：

let alert = UIAlertController(title: nil, message: nil, preferredStyle: .alert)
    alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
    let saveAction = UIAlertAction(title:"Save", style: .destructive, handler: { (action) -> Void in

    })
    alert.addAction(saveAction)
    alert.addTextField(configurationHandler: { (textField) in
        textField.placeholder = "Enter something"
        NotificationCenter.default.addObserver(forName: UITextField.textDidChangeNotification, object: textField, queue: OperationQueue.main) { (notification) in
            saveAction.isEnabled = textField.text?.count > 0
        }
    })
    present(alert, animated: true, completion: nil)

【讨论】：

    【解决方案5】：

    这可以在显示警报控制器之前通过 NSNotificationCenter 来实现，你所要做的就是让通知中心观察 UITextFieldTextDidChangeNotification 的通知，你应该很好，

    下面给出的是相同的实现

    @IBAction func showAlert(sender: AnyObject) {

    var alert = UIAlertController(title: "New user",
        message: "Add a new user",
        preferredStyle: .Alert)

    let saveAction = UIAlertAction(title: "Save",
        style: .Default) { (action: UIAlertAction!) -> Void in

            println("do your stuff here")
    }

    saveAction.enabled = false

    let cancelAction = UIAlertAction(title: "Cancel",
        style: .Default) { (action: UIAlertAction!) -> Void in
    }


    alert.addTextFieldWithConfigurationHandler {
        (textFieldName: UITextField!) in
        textFieldName.placeholder = "Enter full name"
    }

    alert.addTextFieldWithConfigurationHandler {
        (textFieldEmail: UITextField!) in
        textFieldEmail.placeholder = "Enter valid email adress"
        textFieldEmail.keyboardType = .EmailAddress

    }
// adding the notification observer here
 NSNotificationCenter.defaultCenter().addObserverForName(UITextFieldTextDidChangeNotification, object:alert.textFields?[0],
        queue: NSOperationQueue.mainQueue()) { (notification) -> Void in

            let textFieldName = alert.textFields?[0] as! UITextField
            let textFieldEmail = alert.textFields![1] as! UITextField
            saveAction.enabled = self.isValidEmail(textFieldEmail.text) &&  !textFieldName.text.isEmpty
    }


    NSNotificationCenter.defaultCenter().addObserverForName(UITextFieldTextDidChangeNotification, object:alert.textFields?[1],
        queue: NSOperationQueue.mainQueue()) { (notification) -> Void in

            let textFieldEmail = alert.textFields?[1] as! UITextField
            let textFieldName = alert.textFields?[0] as! UITextField
            saveAction.enabled = self.isValidEmail(textFieldEmail.text) &&  !textFieldName.text.isEmpty
    }


    alert.addAction(saveAction)
    alert.addAction(cancelAction)

    presentViewController(alert,
        animated: true,
        completion: nil)

}

 //  email validation code method
func isValidEmail(testStr:String) -> Bool {
    let emailRegEx = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"
    if let emailTest = NSPredicate(format:"SELF MATCHES %@", emailRegEx) as NSPredicate? {
        return emailTest.evaluateWithObject(testStr)
    }
    return false
}

    【讨论】：

    • 非常感谢，这有所帮助，但行为有点奇怪。如果我先输入姓名，然后输入电子邮件，则可以，但如果我先输入电子邮件，然后输入姓名，则没有任何反应。此外，当输入电子邮件并从名称字段中删除文本时，它仍然允许我发送信息：S
    • @MarkoMiletić：嗯，我刚刚给了你关于如何执行保存按钮的想法，等我更新我的答案
    • @MarkoMiletić 完成的编辑将根据您的需要进行，请查看并告诉我
    • @MarkoMiletić：有一个缺陷，所以重新编辑代码请确认
    • 是的，这就是解决方案，但是正如@keithbhunter 所写的，这两个文本字段都需要在两个通知中进行验证。非常感谢:)
    【解决方案6】：

    您可以使用下面的代码来验证 UIAlertController 中的文本字段：-

    第 1 步：

    Declare "email_TF" to your viewcontroller.h 

for example: 
    @property(strong,nonatomic)UITextField *email_TF;

    第 2 步：

    UIAlertController *alert= [UIAlertController alertControllerWithTitle:@"Forgot Password?" message:nil preferredStyle:UIAlertControllerStyleAlert];
[alert addTextFieldWithConfigurationHandler: ^(UITextField *textField){
    textField.placeholder= @"Enter Your Valid Email";
    textField.autocorrectionType= UITextAutocorrectionTypeYes;
    textField.keyboardType= UIKeyboardTypeEmailAddress;

    email_TF= textField;
}];

    第 3 步：

    UIAlertAction *noButton= [UIAlertAction actionWithTitle:@"No, thanks" style:UIAlertActionStyleDestructive handler:^(UIAlertAction *action){
    //Handel no, thanks button
}];
[alert addAction:noButton];

UIAlertAction *yesButton= [UIAlertAction actionWithTitle:@"Yes, please" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action){
    //Handel your yes please button action here
    NSLog(@"%@", email_TF.text);

    if(email_TF.text.length>0){//

        NSString *emailString= email_TF.text;
        NSString *emailReg= @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
        NSPredicate *emailTest= [NSPredicate predicateWithFormat:@"SELF MATCHES %@",emailReg];

        if(([emailTest evaluateWithObject:emailString]!=YES) || [emailString isEqualToString:@""]){

            UIAlertView *loginalert= [[UIAlertView alloc] initWithTitle:@"Forgot Password !" message:@"\nPlease enter valid Email (example@example.com format) ." delegate:self cancelButtonTitle:@"Ok" otherButtonTitles: nil];
            [loginalert show];

        }else{

            NSLog(@"your TextField successfully validated");

        }
    }else{

        UIAlertView *alert= [[UIAlertView alloc] initWithTitle:@"Forgot Password !" message:@"\nPlease Enter Your Email..." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];

    }

}];

[alert addAction:yesButton];

    第 4 步：

    [self presentViewController:alert animated:YES completion:nil];

    【讨论】：

      【解决方案7】：

      注册文本字段更改通知并验证那里的文本字段：

      //...
alert.addTextFieldWithConfigurationHandler {
    (textFieldEmail: UITextField!) in
    textFieldEmail.placeholder = "Enter valid email adress"
    textFieldEmail.keyboardType = .EmailAddress
}   

let textFieldValidationObserver: (NSNotification!) -> Void = { _ in
    let textFieldName = alert.textFields![0] as! UITextField
    let textFieldEmail = alert.textFields![1] as! UITextField
    saveAction.enabled = self.isValidEmail(textFieldEmail.text) && textFieldName.text.length > 0
}

// Notifications for textFieldName changes
NSNotificationCenter.defaultCenter().addObserverForName(UITextFieldTextDidChangeNotification,
    object: alert.textFields![0],  // textFieldName
    queue: NSOperationQueue.mainQueue(), usingBlock: textFieldValidationObserver)

// Notifications for textFieldEmail changes
NSNotificationCenter.defaultCenter().addObserverForName(UITextFieldTextDidChangeNotification,
    object: alert.textFields![1],  // textFieldEmail
    queue: NSOperationQueue.mainQueue(), usingBlock: textFieldValidationObserver)

alert.addAction(saveAction)
//...

      【讨论】：

      • 我真的很陌生，所以我不太了解它，你能在我的代码中实现它吗？我在“对象：alert.textFields [1]”行上收到错误消息，上面写着“'[AnyObject]' 没有名为 'subscript' 的成员”
      • 更新了我的答案。注意隐式展开的选项。这就是我之前错过的以及导致您的错误的原因。
      • 哦，谢谢老兄！！！这成功了 :) 我通常从事前端开发工作，所以这类事情对我来说有点像中文 :D
      【解决方案8】：

      我实现了a UIAlertController subclass，它允许您在将文本字段更改添加到警报时添加处理程序：

      public class TextEnabledAlertController: UIAlertController {
  private var textFieldActions = [UITextField: ((UITextField)->Void)]()

  func addTextField(configurationHandler: ((UITextField) -> Void)? = nil, textChangeAction:((UITextField)->Void)?) {
    super.addTextField(configurationHandler: { (textField) in
        configurationHandler?(textField)

        if let textChangeAction = textChangeAction {
            self.textFieldActions[textField] = textChangeAction
            textField.addTarget(self, action: #selector(self.textFieldChanged), for: .editingChanged)

        }
    })
  }

  @objc private func textFieldChanged(sender: UITextField) {
    if let textChangeAction = textFieldActions[sender] {
        textChangeAction(sender)
    }
  }
}

      因此，对于您的情况，唯一需要添加的是在 textChangeAction 处理程序中调用 isValidEmail 函数：

          alert.addTextField(configurationHandler: { (textField) in
        // things you want to configure on the textfield
    }) { (textField) in
        saveAction.isEnabled = isValidEmail(textField.text ?? "")
    }

      【讨论】：

        【解决方案9】：

        遵循@Kupendiran 提出的使用 UIAlertController 进行电子邮件输入验证的内容。这是一个使用 Objective-C 和更新的 UIAlertController 格式的版本，因为 UIAlertView 现在已弃用。

        步骤 1. 将以下内容添加到具有其他属性和变量的 .h 和 .m 文件中

        .h

        @property(strong,nonatomic)UITextField *emailAddressField;

        .m

        UITextField *emailAddressField;

        第 2 步。创建警报消息、按钮和验证过程。

        UIAlertController * alertView =   [UIAlertController
                                           alertControllerWithTitle:@"E-Mail Address"
                                           message:@"Enter your email address:"
                                           preferredStyle:UIAlertControllerStyleAlert];

        [alertView addTextFieldWithConfigurationHandler:^(UITextField *emailTextField) {
            emailTextField.placeholder = @"E-Mail Address";
            emailTextField.autocorrectionType= UITextAutocorrectionTypeYes;
            emailTextField.keyboardType= UIKeyboardTypeEmailAddress;

            emailAddressField = emailTextField;
        }];

        第 3 步。创建警报操作

                UIAlertAction * ok= [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action){
            //Handel your OK button action here
            NSLog(@"Email Address Entered is: %@", emailAddressField.text);

            //Validate email address is correct format
            if(emailAddressField.text.length>0){//

                NSString *emailString= emailAddressField.text;
                NSString *emailReg= @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
                NSPredicate *emailTest= [NSPredicate predicateWithFormat:@"SELF MATCHES %@",emailReg];

                if(([emailTest evaluateWithObject:emailString]!=YES) || [emailString isEqualToString:@""]){

                    NSLog(@"Email Address Entered is not valid: %@", emailAddressField.text);

                    UIAlertController *badEmailAlert = [UIAlertController
                                                     alertControllerWithTitle:@"Email Address"
                                                                      message:@"\nPlease enter valid Email (example@example.com format) ."
                                                               preferredStyle:UIAlertControllerStyleAlert];
                    [self presentViewController:badEmailAlert animated:YES completion:nil];

                    UIAlertAction* cancel = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleDefault
                                                                   handler:^(UIAlertAction * action) {
                                                                       [badEmailAlert dismissViewControllerAnimated:YES completion:nil];
                                                                       [self presentViewController:alertView animated:YES completion:nil];
                                                                   }];
                    [badEmailAlert addAction:cancel];


                }else{

                    NSLog(@"your TextField successfully validated");

                }
            }else{

                [self presentViewController:alertView animated:YES completion:nil];

            }

        }];
        [alertView addAction:ok];


        //Handel your Cancel button action here
        UIAlertAction* cancel = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleDefault
                                                       handler:^(UIAlertAction * action) {
                                                           [alertView dismissViewControllerAnimated:YES completion:nil];
                                                       }];
        [alertView addAction:cancel];

        第 4 步。在屏幕上显示警报消息

        [self presentViewController:alertView animated:YES completion:nil];

        【讨论】：

          【解决方案10】：

          首先，您需要在类中添加一些变量：

          private weak var saveAction : UIAlertAction?
private weak var textFieldName : UITextField?
private weak var textFieldEmail : UITextField?
private var validName = false
private var validEmail = false

          然后，当你要配置警报控制器时（我只粘贴了需要更改的东西）：

              alert.addTextFieldWithConfigurationHandler {
        (textFieldName: UITextField!) in
        textFieldName.placeholder = "Enter full name"
        textFieldName.delegate = self
        self.textFieldName = textFieldName
    }
    alert.addTextFieldWithConfigurationHandler {
        (textFieldEmail: UITextField!) in
        textFieldEmail.placeholder = "Enter valid email adress"
        textFieldEmail.keyboardType = .EmailAddress
        textFieldEmail.delegate = self
        self.textFieldEmail = textFieldEmail
    }

    let saveAction = UIAlertAction(title: "Save",
        style: .Default) { (action: UIAlertAction!) -> Void in
        // here you are sure the name and email are correct
        let name = (alert.textFields[0] as! UITextField).text
        let email = (alert.textFields[1] as! UITextField).text
    }

    saveAction.enabled = false
    self.saveAction = saveAction

          最后，你应该实现这个委托方法：

          func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {

    let newText = NSString(string: textField.text).stringByReplacingCharactersInRange(range, withString: string)

    if textField == self.textFieldName {
        // validate newText for the name requirements
        validName = self.validateName(newText)
    } else if textField == self.textFieldEmail {
        // validate newText for the email requirements
        validEmail = self.validateEmail(newText)
    }

    self.saveAction?.enabled = validEmail && validName

    return true
}

          【讨论】：

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