waiting for users response in swift - ios

Question

I created an alert:
var a = 0 // default
let userAction = UIAlertController(title: "Select", message: "Select an action", preferredStyle: UIAlertControllerStyle.alert)
userAction.addAction(UIAlertAction(title: "action 1", style: .default, handler: { (action: UIAlertAction!) in
a = 1
}))
userAction.addAction(UIAlertAction(title: "action 2", style: .cancel, handler: { (action: UIAlertAction!) in
a = 2
}))
present(userAction, animated: true, completion: nil)
let resp = Just.get("http://localhost/\(a)").text
return resp
and after this code i'm sending a request with a parameter(a) but request is sent before choosing an action.
how can i wait till user choose and action from alert?

Answer 1

Remove your call function below the present call. Move it to your alert button action closure
var a = 0 // default
let userAction = UIAlertController(title: "Select", message: "Select an
action", preferredStyle: UIAlertControllerStyle.alert)
userAction.addAction(UIAlertAction(title: "action 1", style: .default,
handler: { (action: UIAlertAction!) in
a = 1
// Call function here
}))
userAction.addAction(UIAlertAction(title: "action 2", style: .cancel,
handler: { (action: UIAlertAction!) in
a = 2
// Call function here
}))
present(userAction, animated: true, completion: nil)

Answer 2

you can use semaphore to wait process until get signal.
Have a look at this tutorial https://medium.com/swiftly-swift/a-quick-look-at-semaphores-6b7b85233ddb, it's for GCD, but we can use it for main queue also.
Simply create let semaphore = DispatchSemaphore(value: 1) , then semaphore.wait() - wait until its get signal through semaphore.signal().
Have a look at tutorial link for more information.

Answer 3

Try doing it like this
let alertView = UIAlertController.init(title: "Enviado com sucesso!", message: "O seu bilhete foi enviado com sucesso", preferredStyle: .alert)
let OKAction = UIAlertAction(title: "OK", style: .default) { action in
//the Code you place here Will be called after user Select an action
}
alertView.addAction(OKAction)
self.present(alertView, animated: true, completion: nil)

Answer 4

Declare typealias on top of class like
import UIKit
typealias Request = ((_ value:String) -> ())
then your method :-
func showPopup( completion:#escaping Request) {
var a = 0 // default
let userAction = UIAlertController(title: "Select", message: "Select an action", preferredStyle: UIAlertControllerStyle.alert)
userAction.addAction(UIAlertAction(title: "action 1", style: .default, handler: { (action: UIAlertAction!) in
a = 1
let resp = Just.get("http://localhost/\(a)").text
completion(resp)
}))
userAction.addAction(UIAlertAction(title: "action 2", style: .cancel, handler: { (action: UIAlertAction!) in
a = 2
let resp = Just.get("http://localhost/\(a)").text
completion(resp)
}))
self.present(userAction, animated: true, completion: nil)
}
and call your method where you want like this:-
self.showPopup{ (value) in
print(value)
}