在后台继续执行任务

我在这里遗漏了多任务处理功能。我知道我们可以在后台执行任务，但我真正需要的是当应用程序进入后台时任务继续执行。所以我需要的不同于在后台开始新任务。如果在视图中加载图像并且用户按下主页按钮以使应用程序进入后台，我希望继续加载图像，当用户再次激活应用程序时，他可以看到所有加载的图像。如何才能做到这一点？非常感谢。

Am I missing something here with Multitasking feature. I know we can execute a task in background, but what I really need is that task continues execution when app goes in background. So what I need is different than starting a new task in background. If images are being loaded in a view and user presses the home button to make the app go in background, I want that images continue to load and when user makes the app active again, he can see all the loaded images. How can this be done? Thanks a lot.