iphone streaming video/audio and save it

I would like to have nice player in the iPhone. The source is audio/video files from the server (for example, MP3/M4V). Let's imagine, the file is huge hence I need to stream it inside iPhone. I been researching and there are lots of possibility to do this, MPMoviePlayer or AVPlayer with AVURLAsset. I am able to do that, but now the challenge, how do you streaming the file and after finished download you save it to iphone? so that next time user does not need to re-download it again.

I been thinking to use AVAssetReader and A开发者_StackOverflow中文版VAssetWriter and use CMSampleBufferRef. Anybody has another thought about this?

Thanks!

I been communicating with Apple AV Developer and he confirmed that it is not possible to do this.