如何实现Web资源的缓存？ NSURLRequest缓存还是磁盘缓存？

I have several UITableViews that asynchronously load the images, video, and text from the internet using NSURLRequest and NSURLConnection (Think similar to NYTimes app). That works fine. Currently the content isn't cached. I don't need offline access but just want to cache to speed up performance.I have several UITableViews that asynchronously