隐藏警报控制器之前检查文本字段中的值-iOS Swift

Question

What I am trying to do is that I am taking user's contact number (mobile number) if it is correct then it should continue the signup otherwise the alert controller should not hide and show some error

let alertController = UIAlertController(title: "Phone Number", message: "Please enter your number", preferredStyle: .alert)
alertController.addTextField {
     (textField) -> Void in
      textField.tag = 128
      textField.delegate = self
      textField.placeholder = "923xxxxxxxxx"
}
alertController.addAction(UIAlertAction(title: "Continue", style: .default, handler: {
      alert -> Void in
      let textField = alertController.textFields![0] as UITextField

      if (textField.text?.count)! == 12 && ((textField.text?.substring(to: 3))!) == "923" {
          //my code

      }
      else {
          //should show/keep alert controler
      }
}))             
self.present(alertController, animated: true, completion: nil)

Answer 1

You could disable the button ( UIAlertAction ) by default. Then listen to text changes in your UITextField and update the button accordingly:

var autoEnableAlertAction: UIAlertAction?

func presentAlertController() {
    // alert controller
    let ac = UIAlertController(title: "Registration", message: "Please enter your phone number.", preferredStyle: .Alert)

    // alert action - disabled by default
    let okAction = UIAlertAction(title: "OK", style: .Default, handler: nil)
    okAction.enabled = false
    ac.addAction(okAction)

    // store a reference to the alert action to enable / disable it later
    autoEnableAlertAction = okAction

    ac.addTextFieldWithConfigurationHandler { tf in
        // listen for changes in the textfield
        tf.addTarget(self, action: #selector(self.checkTextFieldText(_:)), forControlEvents: .EditingChanged)
    }

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

@objc func checkTextFieldText(textField: UITextField) {
    autoEnableAlertAction?.enabled = textField.text?.characters.count >= 5
}

Sorry for my answer being a Swift 2 version... :)

Answer 2

Try out this,

let alertController = UIAlertController(title: "Phone Number", message: "Please enter your number", preferredStyle: .alert)
alertController.addTextField {
    (textField) -> Void in
    textField.tag = 128
    textField.delegate = self
    textField.placeholder = "923xxxxxxxxx"
}
alertController.addAction(UIAlertAction(title: "Continue", style: .default, handler: {
    alert -> Void in
    let textField = alertController.textFields![0] as UITextField
    if (textField.text?.count)! == 12 && ((textField.text?.substring(to: 3))!) == "923"
      {
        //my code
    }
    else
    {
        //alert with error
        let alertControllerError = UIAlertController(title: "error", message: "error here", preferredStyle: .alert)

        alertControllerError.addAction(UIAlertAction(title: "ok", style: .default, handler: { alert -> Void in

        }))
        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + .seconds(1)) {
            self.present(alertControllerError, animated: true, completion: nil)
        }
    }
}))
self.present(alertController, animated: true, completion: nil)

Answer 3

func presentAlertController()
{
    let alertController = UIAlertController(title: "Phone Number", message: "Please enter your number", preferredStyle: .alert)
    alertController.addTextField {
        (textField) -> Void in
        textField.tag = 128
        textField.placeholder = "923xxxxxxxxx"
    }
    alertController.addAction(UIAlertAction(title: "Continue", style: .default, handler: {
        alert -> Void in
        let textField = alertController.textFields![0] as UITextField

        if (textField.text?.count)! == 12 && textField.text?.prefix(3) == "923"
        {
            print("sucess")

        }
        else
        {
            print("Incorrect Number")


            DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + .seconds(2)) {
                self.presentAlertController(parameters: parameters)
            }
        }
    }))

    alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler:{
        alert -> Void in
    }))

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