Swift calling a ViewController function from the AppDelegate

Question

Is it possible to run a function defined in a view controller from the AppDelegate function applicationWillEnterForeground? If so, how? I am trying to do this in applicationWillEnterForeground but vc is nil.

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
         return true
    }
    
    func applicatioWillEnterForeground (_ application: UIApplication) {
        
        if let vc = window?.rootViewController as? ViewController {
             vc.resetValues()
    }

}

That could work indeed, if the `rootViewController` is `ViewController`, but maybe it's simpler to listen to the Notification willEnterForeground inside `ViewController` and call `resetValues()`. See https://stackoverflow.com/questions/25716012/triggering-a-specific-action-when-the-app-enters-foreground-from-a-local-notific notification which in recent Swift version has been renamed: https://developer.apple.com/documentation/uikit/uiapplication/1622944-willenterforegroundnotification — Larme, Oct 02 '21 at 16:32
By the way, be very careful in the method names. Note the typo in `applicatioWillEnterForeground`. Probably just a type introduced when composing the question, but FWIW… — Rob, Oct 02 '21 at 16:57

Swift calling a ViewController function from the AppDelegate

0 Answers0