Function after presenting Alert Swift

Question

TLDR
Is there a way to be notified before a UIAlert is going to be presented. Is there a viewDidLoad/viewWillLoad type function that can be called in a ViewController either before or after an alert pops up?

My Problem
My View Controller is receiving an alert from a method in my app delegate. My View Controller calls a method in the app delegate which can then send a UIAlert if there was a problem. While this seems like bad design, I can't change it. I need some type of way of knowing that an alert showed up.

I misunderstood my own code, but thanks for the useful answers. I hope this helps someone else — Matt Bart, Jun 21 '18 at 01:51

Shehata Gamal · Accepted Answer · 2018-06-21T00:18:45.183

You can try

// do before 
self.present(alert,animated:true) {
    // do after
}

Sol1:

Add a completion block when you call the Appdelegate func and inside app delegate return that completion like code above in // do after

Sol2:

set a delegate between app delegate and the VC that calls it

Sol3:

use

 NotificationCenter.default.addObserver(
        self,
        selector: #selector(listenForNotification),
        name: Notification.Name(rawValue: "AlertShowed"),
        object: nil)

inside the VC

and this in Appdelagete alert completion

 NotificationCenter.default.post(name: Notification.Name("AlertShowed"), object:"")

score 0 · Answer 2 · answered Jun 20 '18 at 23:26

The function present(_:animated:completion:) takes an Optional completion handler, completion. If you provide a completion handler it gets called once the modal is displayed. You display UIAlertControllers using present(_:animated:completion:), so just pass in a completion handler.

score 0 · Answer 3 · answered Jun 21 '18 at 00:12

If you are opening the alert from within a method in appdelegate, then you should some how keep a reference on your view controller and call a specific method on it before showing the alert.

Or even, you can implement a pub sub design where you’d have your controller register for a custom notification name on the Notification Center and call/post that notification from the appdelegate just before showing the alert, don’t forget about removing the observer once the controller gets closed.

The choice is yours

Function after presenting Alert Swift

3 Answers3