iOS Background task never launched - ios

Question

This code is supposed to regularly schedule a background task.
Running on a device, I never ever see the "background refresh started" log that would prove the task has been scheduled by the system.
Everything else runs fine.
When I use the "force background task launch trick" by typing e -l objc -- (void)[[BGTaskScheduler sharedScheduler] _simulateLaunchForTaskWithIdentifier:#"TaskIdentifier"] in the console I do see the task being executed.
I have Background fetch and Background Processing activated in the target capabilities.
So why is the system not schedule the task ?
class AppDelegate: UIResponder, UIApplicationDelegate {
func application(_ application: UIApplication,
didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
MSLogger.debug("Application Event : didFinishLaunchingWithOptions")
// Register the background refresh handler and schedule it
registerForBackgroundRefresh()
scheduleNextRefresh()
return true
}
//------------------------------------------------------------------------------------------------------------------
// MARK: - Background refresh management
let backgroundTaskIdentifier = "TaskIdentifier"
func registerForBackgroundRefresh() {
let crd = BGTaskScheduler.shared.register(forTaskWithIdentifier: backgroundTaskIdentifier,
using: nil) {
task in
self.handleBackgroundRefresh(task: task as! BGAppRefreshTask)
}
MSLogger.debug("task registration : \(crd)")
}
func scheduleNextRefresh() {
// Schedule the next refresh for within 2 hours
let request = BGAppRefreshTaskRequest(identifier: backgroundTaskIdentifier)
request.earliestBeginDate = Date(timeIntervalSinceNow: 30 /*2 * 3600##*/)
do {
try BGTaskScheduler.shared.submit(request)
MSLogger.debug("submit background task request")
} catch {
MSLogger.debug("Could not schedule app refresh: \(error.localizedDescription)")
}
}
func handleBackgroundRefresh(task: BGAppRefreshTask) {
MSLogger.debug("background refresh started")
let queue = OperationQueue()
queue.maxConcurrentOperationCount = 1
let operation = BlockOperation {
// Do something
}
task.expirationHandler = {
// After all operations are cancelled, the completion block below is called to set the task to complete.
queue.cancelAllOperations()
self.scheduleNextRefresh()
}
operation.completionBlock = {
task.setTaskCompleted(success: operation.isCancelled)
self.scheduleNextRefresh()
}
queue.addOperation(operation)
}
}