ios - 不关闭 View 的 UIAlertController 操作

Question

我创建了一个 UIAlertController，其中包含一个文本字段和一个将验证码发送到用户电话号码的操作。但是，该操作也会关闭警报 Controller ，使用户无法输入验证码。有没有办法使警报操作不关闭警报 Controller ？

   let alertController = UIAlertController(title: "Verification", message: "a code has been sent to your phone number", preferredStyle: .alert)

let confirm = UIAlertAction(title: "Confirm", style: .default, handler: {
    alert -> Void in
    //verifies code
})

let resend = UIAlertAction(title: "Resend", style: .default, handler: {
        alert -> Void in
        //resends code
    })

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

})

alertController.addTextField { (textField : UITextField!) -> Void in
    textField.placeholder = "Enter code"
}

alertController.addAction(confirm)
alertController.addAction(resend)
alertController.addAction(cancelAction)

self.present(alertController, animated: true, completion: nil)

Answer 1

您可以使用UITextFieldDelegate和 isEnabled UIAlertAction的属性(property)达到预期的效果。

步骤:

1. 您的类(class)应确认 UITextFieldDelegate
2. 您的警报操作应声明为类级别属性
3. 在显示警报之前禁用警报操作
4. 配置文本字段并将 delegate 设置为您的类
5. 实现 shouldChangeCharactersIn: 方法
6. 如果文本长度大于所需长度，则启用警报操作，否则禁用警报操作

代码:

// Your Class should confirm to UITextFieldDelegate
class ViewController: UIViewController, UITextFieldDelegate
{
    // Verify alert action, alert button that want to be disabled
    var verifyAction : UIAlertAction!

    // Shows the alert
    @IBAction func showAlert(sender : UIButton)
    {
        let alert    = UIAlertController(title: "Verify", message: "Please Enter the verification code to continue", preferredStyle: UIAlertControllerStyle.alert)
        verifyAction = UIAlertAction(title: "Verify", style: UIAlertActionStyle.default) { (action) in
            // Do verification and other stuffs
        }

        // Configures textfield properties and delegate
        alert.addTextField { (textField) in
            textField.placeholder = "Verification Code"
            textField.delegate    = self
        }

        // Disables the button
        verifyAction.isEnabled = false
        alert.addAction(verifyAction)
        self.present(alert, animated: true, completion: nil)
    }

    // Textfield delegate method for observing the text change
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool
    {
        // if text length is greater than 0 enables the button, else disables it
        let existingText = textField.text as NSString?
        if let replacedText = existingText?.replacingCharacters(in: range, with: string), replacedText.characters.count > 0
        {
            verifyAction.isEnabled = true
        }
        else
        {
            verifyAction.isEnabled = false
        }
        return true
    }
}

注意:我在发布代码之前写了这个答案，因此它不是基于您在问题中提供的代码。这是一个通用答案，如果您希望我这样做，我会编辑答案。