26  

You can add multiple textfields to alert controller and access them with alert controller's textFields property

您可以向警报控制器添加多个文本字段，并使用警报控制器的textFields属性访问它们

If new password is empty string, present the alert again. Or another way.. first disable Confirm button, enable it only when text field has text

如果新密码为空字符串，则再次显示警报。或者另一种方式..首先禁用“确认”按钮，仅在文本字段包含文本时启用它

UIAlertAction *okAction = [UIAlertAction actionWithTitle:@"confirm the modification" style:UIAlertActionStyleDestructive handler:^(UIAlertAction * _Nonnull action) {
    UITextField *password = alertController.textFields.firstObject;
    if (![password.text isEqualToString:@""]) {

        //change password

    }
    else{
        [self presentViewController:alertController animated:YES completion:nil];
    }
}];

44  

You will get all added textfields from alert controller by its textFields readonly property, you can use it to get its text. Like

您将通过其textFields readonly属性从警报控制器获取所有添加的文本字段，您可以使用它来获取其文本。喜欢

Swift 4:

斯威夫特4：

let alertController = UIAlertController(title: "", message: "", preferredStyle: .alert)
alertController.addTextField { textField in
    textField.placeholder = "Password"
    textField.isSecureTextEntry = true
}
let confirmAction = UIAlertAction(title: "OK", style: .default) { [weak alertController] _ in
    guard let alertController = alertController, let textField = alertController.textFields?.first else { return }
    print("Current password \(String(describing: textField.text))")
    //compare the current password and do action here
}
alertController.addAction(confirmAction)
let cancelAction = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)
alertController.addAction(cancelAction)
present(alertController, animated: true, completion: nil)

Note: textField.text is optional, unwrap it before using

注意：textField.text是可选的，在使用之前将其解包

Objective-C:

Objective-C的：

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"" message:@"" preferredStyle:UIAlertControllerStyleAlert];
[alertController addTextFieldWithConfigurationHandler:^(UITextField * _Nonnull textField) {
    textField.placeholder = @"Current password";
    textField.secureTextEntry = YES;
}];
UIAlertAction *confirmAction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
    NSLog(@"Current password %@", [[alertController textFields][0] text]);
    //compare the current password and do action here

}];
[alertController addAction:confirmAction];
UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
    NSLog(@"Canelled");
}];
[alertController addAction:cancelAction];
[self presentViewController:alertController animated:YES completion:nil];

By [[alertController textFields][0] text] this line, it will take first textfield added to the alerController and get its text.

通过[[alertController textFields] [0] text]这一行，它将第一个文本字段添加到alerController并获取其文本。

10  

Here is an updated answer for Swift 4.0 that creates the desired kind of textfield:

以下是Swift 4.0的更新答案，它创建了所需的文本字段：

// Create a standard UIAlertController
let alertController = UIAlertController(title: "Password Entry", message: "", preferredStyle: .alert)

// Add a textField to your controller, with a placeholder value & secure entry enabled
alertController.addTextField { textField in
    textField.placeholder = "Enter password"
    textField.isSecureTextEntry = true
    textField.textAlignment = .center
}

// A cancel action
let cancelAction = UIAlertAction(title: "Cancel", style: .cancel) { _ in
    print("Canelled")
}

// This action handles your confirmation action
let confirmAction = UIAlertAction(title: "OK", style: .default) { _ in
    print("Current password value: \(alertController.textFields?.first?.text ?? "None")")
}

// Add the actions, the order here does not matter
alertController.addAction(cancelAction)
alertController.addAction(confirmAction)

// Present to user
present(alertController, animated: true, completion: nil)

And how it looks when first presented:

它首次呈现时的外观如何：

And while accepting text:

在接受文字的同时：