static async Task <ENManager> GetManagerAsync()
{
if (manager == null)
{
manager = new ENManager();
await manager.ActivateAsync();
}
return(manager);
}
public static Task PlatformScheduleFetch()
{
string logPrefix = $"{nameof(BackgroundServiceHandler)}.{nameof(PlatformScheduleFetch)}: ";
// iOS 12.5
if (AppDelegate.ShouldOperateIn12_5Mode)
{
if (ObjCRuntime.Class.GetHandle("ENManager") == IntPtr.Zero)
{
LogUtils.LogException(Enums.LogSeverity.ERROR,
new NullReferenceException("Pointer to ENManager is null"),
logPrefix + "Failed to retrieve ENManager instance [iOS 12.5 mode]");
return(null);
}
ENManager manager = new ENManager();
manager.SetLaunchActivityHandler(activityFlags =>
{
if (activityFlags.HasFlag(ENActivityFlags.PeriodicRun))
{
Task.Run(async() =>
{
CancellationTokenSource cancelSrc = new CancellationTokenSource();
try
{
await Xamarin.ExposureNotifications.ExposureNotification.UpdateKeysFromServer(cancelSrc.Token);
}
catch (OperationCanceledException e)
{
LogUtils.LogException(Enums.LogSeverity.WARNING, e, logPrefix + "Background task took too long to complete [iOS 12.5 mode]");
}
catch (NSErrorException nserror)
{
if (nserror.Domain == "ENErrorDomain")
{
LogUtils.LogException(Enums.LogSeverity.WARNING, nserror, logPrefix + $"Background task failed due to EN API Error Code={nserror.Code} [iOS 12.5 mode]");
}
else
{
LogUtils.LogException(Enums.LogSeverity.WARNING, nserror, logPrefix + $"Background task failed due to NSError {nserror.Domain} {nserror.Code}. [iOS 12.5 mode]");
}
}
catch (Exception ex)
{
LogUtils.LogException(Enums.LogSeverity.WARNING, ex, logPrefix + $"Background task: An error occurred inside the async task [iOS 12.5 mode]");
}
});
}
});
return(manager.ActivateAsync());
}
// iOS 13+
// This is a special ID suffix which iOS treats a certain way
// we can basically request infinite background tasks
// and iOS will throttle it sensibly for us.
string id = CommonServiceLocator.ServiceLocator.Current.GetInstance <IAppInfo>().PackageName + ".exposure-notification";
BGTaskScheduler.Shared.Register(id, null, async task =>
{
try
{
if (ENManager.AuthorizationStatus != ENAuthorizationStatus.Authorized) // ENManager is not authorised yet
{
Debug.WriteLine(logPrefix + "ENManager AuthorizationStatus isn't authorized");
scheduleBgTask(0); // reschedule to try in the future
return;
}
bool shouldFetch = await Xamarin.ExposureNotifications.ExposureNotification.IsEnabledAsync();
if (!shouldFetch)
{
LogUtils.LogMessage(Enums.LogSeverity.WARNING, logPrefix + "Did not pull. EN was not enabled (iOS)");
}
System.Diagnostics.Debug.WriteLine($"Background Task is fetching: {shouldFetch}");
if (shouldFetch)
{
CancellationTokenSource cancelSrc = new CancellationTokenSource();
task.ExpirationHandler = cancelSrc.Cancel;
// Run the actual task on a background thread
await Task.Run(async() =>
{
try
{
await Xamarin.ExposureNotifications.ExposureNotification.UpdateKeysFromServer(cancelSrc.Token);
task.SetTaskCompleted(true);
}
catch (OperationCanceledException e)
{
LogUtils.LogException(Enums.LogSeverity.WARNING, e, logPrefix + "Background task took too long to complete. - BG Task is rescheduled");
task.SetTaskCompleted(false);
}
catch (NSErrorException nserror)
{
if (nserror.Domain == "ENErrorDomain")
{
LogUtils.LogException(Enums.LogSeverity.WARNING, nserror, logPrefix + $"Background task failed due to EN API Error Code={nserror.Code} - BG Task is rescheduled");
task.SetTaskCompleted(false);
}
else
{
LogUtils.LogException(Enums.LogSeverity.WARNING, nserror, logPrefix + $"Background task failed due to NSError {nserror.Domain} {nserror.Code}. - BG Task is rescheduled");
task.SetTaskCompleted(false);
}
}
catch (Exception ex)
{
LogUtils.LogException(Enums.LogSeverity.WARNING, ex, logPrefix + $"Background task: An error occurred inside the async task - BG Task is rescheduled");
task.SetTaskCompleted(false);
}
});
}
}
catch (Exception e)
{
LogUtils.LogException(Enums.LogSeverity.WARNING, e, logPrefix + $"Background task: An error occurred before executing the async task - BG Task is rescheduled");
task.SetTaskCompleted(false);
}
scheduleBgTask(0);
});
scheduleBgTask(0);
return(Task.CompletedTask);
void scheduleBgTask(int numberOfRetries)
{
BGProcessingTaskRequest newBgTask = new BGProcessingTaskRequest(id);
newBgTask.RequiresNetworkConnectivity = true;
try
{
BGTaskScheduler.Shared.Submit(newBgTask, out var error);
if (error != null)
{
if ((BGTaskSchedulerErrorCode)(int)error.Code == BGTaskSchedulerErrorCode.TooManyPendingTaskRequests && numberOfRetries < 5)
{
BGTaskScheduler.Shared.Cancel(id);
scheduleBgTask(++numberOfRetries);
}
else
{
if ((BGTaskSchedulerErrorCode)(int)error.Code == BGTaskSchedulerErrorCode.Unavailable)
{
//This will happen IF:
// - The EN-API permission is not granted/was removed
// AND
// - The “Background app refresh” setting is turned OFF.
}
throw new NSErrorException(error);
}
}
}
catch (Exception ex)
{
LogUtils.LogException(Enums.LogSeverity.ERROR, ex, logPrefix + $"Failed to schedule the background task (Tried 5 times). It will try again when the app is restarted.");
}
}
}
