Actually I am working for multitasking and facing error please assist me, as I need to work on background application and also in foreground application - (void)applicationDidEnterBackground:(UIApplication *)application { UIApplication* app = [UIApplication sharedApplication]; // Request permission to run in the background. Provide an // expiration handler in case the task runs long. NSAssert(bgTask == UIBackgroundTaskInvalid, nil); bgTask = [app beginBackgroundTaskWithExpirationHandler:^{ // Synchronize the cleanup call on the main thread in case // the task actually finishes at around the same time. dispatch_async(dispatch_get_main_queue(), ^{ if (bgTask != UIBackgroundTaskInvalid) { [app endBackgroundTask:bgTask]; bgTask = UIBackgroundTaskInvalid; } }); }]; // Start the long-running task and return immediately. dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{ // Do the work associated with the task. // Synchronize the cleanup call on the main thread in case // the expiration handler is fired at the same time. dispatch_async(dispatch_get_main_queue(), ^{ if (bgTask != UIBackgroundTaskInvalid) { [app endBackgroundTask:bgTask]; bgTask = UIBackgroundTaskInvalid; } }); }); }