Getting text value from alert box - swift

Question

I'm having problems getting a text fields value from a UIAlertController. I am getting the value, but It seems to be executing my code in the wrong order. In the function below, I expect the function call to return a string, but the value is not set at the time the function returns.
#IBAction func btnSaveSession(sender: AnyObject) {
//Prompt user to enter session name
var sessionName: String = ""
sessionName = promptUserToEnterSessionName("Save Session", message: "Please enter the name of your custom session below.");
print("session Name: " + sessionName)
//Save session to firebase.
//redirect to create session controller.
}
func promptUserToEnterSessionName(title: String, message: String) -> String{
var sessionName: String = ""
//1. Create the alert controller.
let alert = UIAlertController(title: title, message: message, preferredStyle: .Alert)
//2. Add the text field. You can configure it however you need.
alert.addTextFieldWithConfigurationHandler({ (textField) -> Void in
textField.text = "Enter session name."
})
//3. Grab the value from the text field, and print it when the user clicks OK.
alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: { (action) -> Void in
let textField = alert.textFields![0] as UITextField
print("Text field: \(textField.text)")
sessionName = textField.text!
}))
// 4. Present the alert.
self.presentViewController(alert, animated: true, completion: nil)
return sessionName
}
If anyone is having problems understanding my question, please comment and I will do my best to explain.

Answer 1

your ok action handler(closure) will call when you click on ok button. so instead of assign value to local variable sessionName , make a sessionName variable in class.
class YourClass {
var sessionName: String?
...
#IBAction func btnSaveSession(sender: AnyObject) {
//Prompt user to enter session name
promptUserToEnterSessionName("Save Session", message: "Please enter the name of your custom session below.");
}
func promptUserToEnterSessionName(title: String, message: String) {
//1. Create the alert controller.
let alert = UIAlertController(title: title, message: message, preferredStyle: .Alert)
//2. Add the text field. You can configure it however you need.
alert.addTextFieldWithConfigurationHandler({ (textField) -> Void in
textField.text = "Enter session name."
})
//3. Grab the value from the text field, and print it when the user clicks OK.
alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: { (action) -> Void in
let textField = alert.textFields![0] as UITextField
print("Text field: \(textField.text)")
self.sessionName = textField.text!
self.testDemo()
}))
// 4. Present the alert.
self.presentViewController(alert, animated: true, completion: nil)
}
fun TestDemo() {
print("session Name: " + self.sessionName)
//Save session to firebase.
//redirect to create session controller.
}
}

Answer 2

You can use a Callback to get the value, like this:
func AlertPrompt(vista:UIViewController, titulo:String , mensaje:String, aceptar:String, completion: #escaping (_ resultado: String)->()) {
let miAlerta = UIAlertController(title: titulo, message: mensaje, preferredStyle: UIAlertControllerStyle.alert)
miAlerta.addTextField(configurationHandler: {
(textField) -> Void in
})
let okBoton = UIAlertAction(title: aceptar, style: UIAlertActionStyle.default, handler: {
(action) -> Void in
let result = miAlerta.textFields![0] as UITextField
// You return the value here
completion(result.text! as String)
})
miAlerta.addAction(okBoton)
let cancelBoton = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.cancel, handler: nil)
miAlerta.addAction(cancelBoton)
vista.present(miAlerta, animated: true, completion: nil)
}
And call the function like this:
AlertPrompt(vista: self, titulo: "Title", mensaje: "some message", aceptar: "Acept"){(resultado)->() in
print(resultado)
}
That works perfect for me, hope this help

Answer 3

This code:
let textField = alert.textFields![0] as UITextField
print("Text field: \(textField.text)")
sessionName = textField.text!
will be called only at the moment the button corresponding to the defined action is clicked. So at the moment of creation the UIAlertController it's not called.
Read about blocks in Swift, it should be clearer then.