Swift Nstimer in Background

Run timer in background

It's possible through a token that identifies a request to run in the background.

Like this: var bgTask = UIBackgroundTaskIdentifier()

Here is how to use it:

var bgTask = UIBackgroundTaskIdentifier()
    bgTask = UIApplication.shared.beginBackgroundTask(expirationHandler: {
        UIApplication.shared.endBackgroundTask(bgTask)
    })
    let timer = Timer.scheduledTimer(timeInterval: 10, target: self, selector: #selector(notificationReceived), userInfo: nil, repeats: true)
    RunLoop.current.add(timer, forMode: RunLoopMode.defaultRunLoopMode)

I hope it would be useful!

Scheduled NSTimer when app is in background?

You shouldn't solve this problem by setting a timer, because you're not allowed to execute any code in the background. Imagine what will happen if the user restarts his iPhone in the meantime or with some other edge cases.

Use the applicationDidEnterBackground: and applicationWillEnterForeground: methods of your AppDelegate to get the behavior you want. It's way more robust, because it will also work when your App is completely killed because of a reboot or memory pressure.

You can save the time the timer will fire next when your App is going to the background and check if you should take action when the App comes back to the foreground. Also stop and start the timer in this methods. While your App is running you could use a timer to trigger the update at the right moment.

Related Topics