我正在制作一个音频将在后台播放的应用程序.在以下代码中,bgTask未声明.bgTask应该是什么样的对象？
- (void)applicationDidEnterBackground:(UIApplication *)application
{
UIApplication *app = [UIApplication sharedApplication];
bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{});
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}