How to automatically run a function at 8 am every day? - swift

Question

I'm trying to run a function every day at 8 am , I've tried background fetch with minimum interval 84600(23h 30 min) ,but it doesn't run on my iPhone . What should I do ?
Here is what I wrote in app delegate :
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
FirebaseApp.configure()
GADMobileAds.sharedInstance().start(completionHandler: nil)
UIApplication.shared.setMinimumBackgroundFetchInterval(84600)
return true
}
func applicationWillResignActive(_ application: UIApplication) {
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and invalidate graphics rendering callbacks. Games should use this method to pause the game.
}
func applicationDidEnterBackground(_ application: UIApplication) {
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
func applicationWillEnterForeground(_ application: UIApplication) {
// Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
}
func applicationDidBecomeActive(_ application: UIApplication) {
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
func applicationWillTerminate(_ application: UIApplication) {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}
func application(_ application: UIApplication, shouldSaveApplicationState coder: NSCoder) -> Bool {
return true
}
func application(_ application: UIApplication, shouldRestoreApplicationState coder: NSCoder) -> Bool {
return true
}
func application(_ application: UIApplication, performFetchWithCompletionHandler completionHandler: #escaping (UIBackgroundFetchResult) -> Void) {
let sb = UIStoryboard(name: "Main", bundle: nil)
let activityVC = sb.instantiateViewController(withIdentifier: Constants.Storyboard.activityVC) as! ActivityViewController
activityVC.updateUI()
}
}

Answer 1

You can use a timer constructor like this:
let date = Date().addingTimeInterval(5)
let timer = Timer(fireAt: date, interval: 0, target: self, selector: #selector(runCode), userInfo: nil, repeats: false)
RunLoop.main.add(timer, forMode: .common)
This example launch func runCode after 5 seconds. If you passed repeats to true, and interval to 1, this launch "runCode" after 5 sec and repeats every 1 seconds after.
Now you can change date by your specified date.
source: https://www.hackingwithswift.com/example-code/system/how-to-run-code-at-a-specific-time