如何从警报文本字段中的用户输入获取字符串

Question

i am trying to get a string from user input textfield in an alert like that, but I always get nil value. the code i use to show that alert textfield is like this

 @IBAction func addButtonPressed(_ sender: UIBarButtonItem) {
        // show an alert to show up a quick textfield


        var textField = UITextField()
        let itemTitle = textField.text!

        print("the title is \(itemTitle) ....")


        let alert = UIAlertController(title: "Add Item to your to do list", message: "", preferredStyle: .alert)
        let addItemAction = UIAlertAction(title: "Add item", style: .default) { (action) in
            // after user click "add item", the new item will be displayed to table view

            let newItem = Item()
            newItem.title = itemTitle


            self.itemArray.append(newItem)
            self.saveItems()


        }


        alert.addTextField { (alertTextfield) in
            alertTextfield.placeholder = "Create a new item"
            textField = alertTextfield
            // store a data from user to 'textField' variable, so it can be accessed in closure at 'addItemAction'
        }



        alert.addAction(addItemAction)
        present(alert, animated: true, completion: nil)

    }

My UI

I am trying to print the itemTitle , but i never get the string from the user. like this

Output

what went wrong in here?

Answer 1

You will get that once user pressed Add item not before that where you are trying to print it.

check below code:

let addItemAction = UIAlertAction(title: "Add item", style: .default) { (action) in

    // after user click "add item", the new item will be displayed to table view
    print(textField.text)  //Here you will get user text.

    let newItem = Item()
    newItem.title = textField.text //add it here
    self.itemArray.append(newItem)
    self.saveItems()   
}

Answer 2

You have to get the text from textField when Add Item is pressed.

Change this

newItem.title = itemTitle

to

newItem.title = textField.text

Answer 3

Try this

   /// define alert controller 
  let alert = UIAlertController(title: "Alert Title",
                          message: "Alert message",
                          preferredStyle: UIAlertControllerStyle.alert)

 /// add OK Action
  let ok = UIAlertAction(title: "OK",
                   style: UIAlertActionStyle.default) { (action: UIAlertAction) in

    /// get the textfield instance form textFields array

                    if let alertTextField = alert.textFields?.first, alertTextField.text != nil {

                        print("And the text is... \(alertTextField.text!)!")

                    }


  }

     /// add CANCEL Action

   let cancel = UIAlertAction(title: "Cancel",
                       style: UIAlertActionStyle.cancel,
                       handler: nil)

    /// add first textfeild to the alertController
    alert.addTextField { (textField: UITextField) in

    /// configure textfeild with properties like placeholder and textColor
    textField.placeholder = "Text here"

 }

/// add actions to the alertController

alert.addAction(ok)
alert.addAction(cancel)

/// present alertController in current viewController

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

Answer 4

first of all, let itemTitle = textField.text! will make the itemTitle only assigned once and it will contain empty string as your textField doesn't have any value yet, thats why when you printed it out, it does not return any string.

if you want a messy way to do it, you could keep your code but delete

let itemTitle = textField.text! 

and do what @Bilal said