Background task in iOS action extension

Question

I\'m working on an action extension for an app which prepares some data for the user and then uses MailCore2 to send this information to a SMTP server. Preparing data is done ve

Answer 1

The most useful solution is using push notifications. The solution I used in my own application:

1. Create a simple server which can retrieve a simple request: device token and time when you'd like to wake up your device.
2. When the application goes to background mode send the request to the server to wake up the device later. E.g. 5 minutes/20 minutes, etc. func applicationWillEnterForeground(_ application: UIApplication) { inside AppDelegate.
3. Don't forget to allow the application to work in the background as much as possible.

For example,

   @UIApplicationMain
    class AppDelegate: UIResponder {
    var backgroundTask: UIBackgroundTaskIdentifier = UIBackgroundTaskInvalid
    func application(_ application: UIApplication,
                         didReceiveRemoteNotification userInfo: [AnyHashable: Any],
                         fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
            if UIApplication.shared.applicationState != .active {
                doFetch(completionHandler: completionHandler)
            } else {
                // foreground here
                completionHandler(UIBackgroundFetchResult.noData)
            }
        }
    func application(_ application: UIApplication,
                         performFetchWithCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
            doFetch(completionHandler: completionHandler)
        }
    private func doFetch(completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
    sendTheRequestToWakeApp()
    backgroundTask = UIApplication.shared.beginBackgroundTask { [weak self] in
                self?.endBackgroundTask()
            }
/// do work here
    completionHandler(UIBackgroundFetchResult.noData)
    }
    private func endBackgroundTask() {
            print("Background task ended.")
            UIApplication.shared.endBackgroundTask(backgroundTask)
            backgroundTask = UIBackgroundTaskInvalid
        }
    private func sendTheRequestToWakeApp() {
    /// Implement request using native library or Alamofire. etc.
    }
    }

on server side use simple time or loop.

Disadvantages,

1. Internet is required
2. It doesn't perfectly work. When battery is low the background mode is restricted.

Don't forget to setup the project: