UIAlertController - Waiting for user response - swift

Question

code 3 will be executed despite no response. How to wait for an answer?
let alert = UIAlertController(title: "test", message: "Please answer: yes or not ?", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "Yes", style: .default, handler: { (action) in alert.dismiss(animated: true, completion: nil)
// code 1...
}))
alert.addAction(UIAlertAction(title: "No", style: .default, handler: { (action) in alert.dismiss(animated: true, completion: nil)
// code 2...
}))
self.present(alert, animated: true, completion: nil)
// code 3...

Answer 1

Use closures for the handler parameter, and wait for the user's response:
func checkIfYesOrNo(handler: ((UIAlertAction) -> Void)? = nil) {
let alert = UIAlertController(title: "test", message: "Please answer: yes or not ?", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "Yes", style: .default, handler: handler))
alert.addAction(UIAlertAction(title: "No", style: .default, handler: handler))
present(alert, animated: true, completion: nil)
}
Usage:
checkIfYesOrNo { action in
if action.title == "Yes" {
print("YES")
// code 3...
} else {
print("NO")
// code 3...
}
}

Answer 2

You can create a function to get output of your alert with completion handler like this.. Easy to use
func showAlert(completion: #escaping (Bool) -> Void) {
let alert = UIAlertController(title: "test", message: "Please answer: yes or not ?", preferredStyle: .alert)
// add the actions (buttons)
alert.addAction(UIAlertAction(title: "Yes", style: UIAlertAction.Style.default, handler: {action in
// code 1...
completion(true)
}))
alert.addAction(UIAlertAction(title: "No", style: UIAlertAction.Style.cancel, handler: { action in
// code 2...
completion(false)
}))
present(alert, animated: true, completion: nil)
}
How to use
showAlert { isSuccess in
isSuccess ? print("true") : print("false")
// isSuccess is bool having true or false accordingly
// code 3... here
}