Add background processing

Signed-off-by: Marcel Müller <marcel-mueller@gmx.de>

NextcloudTalk/AppDelegate.m

@@ -85,6 +85,7 @@ - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(
     [NCRoomsManager sharedInstance];
 
     [self registerBackgroundFetchTask];
+    [self registerBackgroundProcessingTask];
 
     [NCUserInterfaceController sharedInstance].mainViewController = (NCSplitViewController *) self.window.rootViewController;
     [NCUserInterfaceController sharedInstance].roomsTableViewController = [NCUserInterfaceController sharedInstance].mainViewController.viewControllers.firstObject.childViewControllers.firstObject;
@@ -141,6 +142,7 @@ - (void)applicationDidEnterBackground:(UIApplication *)application
 
     [self keepExternalSignalingConnectionAliveTemporarily];
     [self scheduleAppRefresh];
+    [self scheduleBackroundProcessing];
 }
 
 
@@ -354,6 +356,56 @@ - (NSString *)stringWithDeviceToken:(NSData *)deviceToken
     return [token copy];
 }
 
+#pragma mark - BackgroundProcessing
+
+- (void)registerBackgroundProcessingTask {
+    NSString *processingTaskIdentifier = [NSString stringWithFormat:@"%@.processing", NSBundle.mainBundle.bundleIdentifier];
+
+    // see: https://developer.apple.com/documentation/backgroundtasks/bgtaskscheduler?language=objc
+    [[BGTaskScheduler sharedScheduler] registerForTaskWithIdentifier:processingTaskIdentifier
+                                                          usingQueue:nil
+                                                       launchHandler:^(__kindof BGTask * _Nonnull task) {
+        [self handleBackgroundProcessing:task];
+    }];
+}
+
+- (void)scheduleBackroundProcessing
+{
+    NSString *processingTaskIdentifier = [NSString stringWithFormat:@"%@.processing", NSBundle.mainBundle.bundleIdentifier];
+
+    BGProcessingTaskRequest *request = [[BGProcessingTaskRequest alloc] initWithIdentifier:processingTaskIdentifier];
+    request.earliestBeginDate = [NSDate dateWithTimeIntervalSinceNow:UIApplicationBackgroundFetchIntervalMinimum];
+    request.requiresNetworkConnectivity = YES;
+    request.requiresExternalPower = NO;
+
+    NSError *error = nil;
+    [[BGTaskScheduler sharedScheduler] submitTaskRequest:request error:&error];
+
+    if (error) {
+        NSLog(@"Failed to submit background processing request: %@", error);
+    }
+}
+
+- (void)handleBackgroundProcessing:(BGTask *)task
+{
+    [NCUtils log:@"Performing background processing -> handleBackgroundProcessing"];
+
+    // With BGTasks (iOS >= 13) we need to schedule another task when running in background
+    [self scheduleBackroundProcessing];
+
+    BGTaskHelper *bgTask = [BGTaskHelper startBackgroundTaskWithName:@"NCBackgroundProcessing" expirationHandler:^(BGTaskHelper *task) {
+        [NCUtils log:@"ExpirationHandler NCBackgroundProcessing called"];
+    }];
+
+    // Check if the shown notifications are still available on the server
+    [[NCNotificationController sharedInstance] checkNotificationExistanceWithCompletionBlock:^(NSError *error) {
+        [NCUtils log:@"CompletionHandler checkNotificationExistance"];
+
+        [task setTaskCompletedWithSuccess:YES];
+        [bgTask stopBackgroundTask];
+    }];
+}
+
 #pragma mark - BackgroundFetch / AppRefresh
 
 - (void)registerBackgroundFetchTask {

NextcloudTalk/Info.plist

@@ -6,6 +6,7 @@
 	<array>
 		<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
 		<string>$(PRODUCT_BUNDLE_IDENTIFIER).refresh</string>
+		<string>$(PRODUCT_BUNDLE_IDENTIFIER).processing</string>
 	</array>
 	<key>CFBundleDevelopmentRegion</key>
 	<string>en</string>