Show UIAlert before unwinding segue - ios

Question

I'm trying to fire an alert that asks if you want to save or delete a draft after pressing cancel. I'm quite close, but I can't seem to get it right.
I'm unwinding from 'ReplyMailViewController'(ViewController A) to 'MailContentViewController'(ViewController B).
I added the following code in ViewController A to show the alert and 'hold' the segue perform:
override func shouldPerformSegue(withIdentifier identifier: String?, sender: Any?) -> Bool {
if let ident = identifier {
if ident == "cancelDraft" {
let saveDraftActionHandler = { (action:UIAlertAction!) -> Void in
NSLog("EXIT")
}
let alertController = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
let deleteDraftAction = UIAlertAction(title: "Delete Draft", style: .destructive, handler: nil)
alertController.addAction(deleteDraftAction)
let saveDraftAction = UIAlertAction(title: "Save Draft", style: .default, handler: saveDraftActionHandler)
alertController.addAction(saveDraftAction)
let cancelAction = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)
alertController.addAction(cancelAction)
present(alertController, animated: true, completion: nil)
return false
}
}
return true
}
The segue holds with this code, but the issue is that I can't figure out how to continue the unwind segue after pressing 'Save Draft' for example.
I also have an unwind function in View Controller B, but I can't seem to figure out how I can use this one for this task:
#IBAction func cancelToMailContentViewController(_ segue: UIStoryboardSegue) {
}

Answer 1

Instead of perform the segue directly you need to show your UIAlertViewController first and according to the user response execute your segue or not
#IBAction func showAlertViewController(){
let alertController = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
let replyAction = UIAlertAction(title: "Delete Draft", style: .destructive, handler: nil)
let replyAllAction = UIAlertAction(title: "Save Draft", style: .default) { (action) in
//Do whatever you need here
}
let cancelAction = UIAlertAction(title: "Cancel", style: .cancel) { (action) in
self.performSegue(withIdentifier: "cancelDraft", sender: action) //executing the segue on cancel
}
alertController.addAction(replyAllAction)
alertController.addAction(replyAction)
alertController.addAction(cancelAction)
present(alertController, animated: true, completion: nil)
}
After this you only need to change the unwind segue action to execute this method, and your segue will be executed if you press cancel in the UIAlertViewController via self.performSegue(withIdentifier: #<SegueIdentifier>, sender: #<sender>)

Answer 2

First, make the alert with two options:
class ViewController: UIViewController {
#IBAction func showAlertButtonTapped(_ sender: UIButton) {
// create the alert
let alert = UIAlertController(title: "UIAlertController", message: "Save this work?", preferredStyle: UIAlertControllerStyle.alert)
// add the actions (buttons)
alert.addAction(UIAlertAction(title: "Hell Yeah", style: UIAlertActionStyle.default, handler: nil))
alert.addAction(UIAlertAction(title: "Hell No", style: UIAlertActionStyle.cancel, handler: nil))
// show the alert
self.present(alert, animated: true, completion: nil)
}
After this, you have to make the segue and then name it (also connect it by control dragging from the view controller yellow icon to the other view controller):
After that put this your code to execute the segue:
self.performSegue(withIdentifier: ":)", sender: self)
After that you are going to execute the segue when the user responds to the alert:
if buttonTitle == "Hell Yeah" {
elf.performSegue(withIdentifier: ":)", sender: self)
}
so, in the end, your code should look like this:
class ViewController: UIViewController {
#IBAction func showAlertButtonTapped(_ sender: UIButton) {
// create the alert
let alert = UIAlertController(title: "UIAlertController", message: "Save this work?", preferredStyle: UIAlertControllerStyle.alert)
// add the actions (buttons)
alert.addAction(UIAlertAction(title: "Hell Yeah", style: UIAlertActionStyle.default, handler: nil))
alert.addAction(UIAlertAction(title: "Hell No", style: UIAlertActionStyle.cancel, handler: nil))
// show the alert
self.present(alert, animated: true, completion: nil)
if buttonTitle == "Hell Yeah" {
self.performSegue(withIdentifier: ":)", sender: self)
}
}
}