Swift: Ignored request to start a new background task because RunningBoard has already started the expiration timer - swift

Question

I have a series of tasks that is triggered by a silent push notification. Upon receiving the push notification, it wakes the iOS up in the background and performs the following tasks:
Opens up a WebViewController that contains a WKWebview
Goes to a webpage, and clicks some buttons automated by javascript injection
Once completed, dismisses the WebViewController
I have added selected BackgroundTasks handlers to manage it by following this tutorial but the console is flooded with the following warning.
[ProcessSuspension] 0x280486080 - WKProcessAssertionBackgroundTaskManager: Ignored request to start a new background task because RunningBoard has already started the expiration timer
Note that the tasks that needs to be done are still performed correctly.
class WebViewController: UIViewController, WKNavigationDelegate, WKScriptMessageHandler {
lazy var webView: WKWebView = {
let v = WKWebView()
v.translatesAutoresizingMaskIntoConstraints = false
v.navigationDelegate = self
return v
}()
var backgroundTask: UIBackgroundTaskIdentifier = .invalid
//Remove BG task when not needed
deinit {
NotificationCenter.default.removeObserver(self)
endBackgroundTask()
}
override func viewDidLoad() {
super.viewDidLoad()
//Register notification for background task
NotificationCenter.default.addObserver(self,
selector: #selector(reinstateBackgroundTask),
name: UIApplication.didBecomeActiveNotification,
object: nil)
registerBackgroundTask()
//Load webview with URL
if let url = url {
let request = URLRequest(url: url)
webView.load(request)
}
}
//MARK:- Handle BG Tasks
func registerBackgroundTask() {
backgroundTask = UIApplication.shared.beginBackgroundTask { [weak self] in
self?.endBackgroundTask()
}
}
func endBackgroundTask() {
Log("Background task ended.")
UIApplication.shared.endBackgroundTask(backgroundTask)
backgroundTask = .invalid
}
#objc func reinstateBackgroundTask() {
if backgroundTask == .invalid {
registerBackgroundTask()
}
}
func endBackgroundTaskIfNotInvalid() {
if backgroundTask != .invalid {
self.endBackgroundTask()
}
}
//This is the final task that needs to be done
fileprivate func updateScheduler(visitedPlace: VisitedPlace) {
if navigator == .scheduler {
if let jobId = jobId {
let data = [
"status": "scheduled",
"completedOn": Date()
] as [String : Any]
///Do some work here...
//Dismiss controller after completing
self.dismiss(animated: true) {
self.endBackgroundTaskIfNotInvalid()
}
}
} else {
self.endBackgroundTaskIfNotInvalid()
}
}
}
What is triggering all these warnings and how do I silence it?

Answer 1

I'm having the same console flood. For me it turned out to be adMob that was the cause.

Answer 2

This happens to me when I run unit tests that wait for test expectations to be filled. I was hoping that it was just a simulator issue, since I don't see it in production, but it sounds like that's not the case.

Answer 3

I fixed the flood by removing the AdMob banner from the view hierarchy on app suspension:
self.bannerView?.removeFromSuperview()
AdMob would still try infrequently which would generate a single log message.