iOS Download/Stream mp3 from RSS Feed

I have an RSS Feed of my podcast containing mp3s. I currently have a php script created that parses the RSS for me, and I display the PHP in webview. When clicked, the mp3s begin playing immediately in a WebView, but there are limitations with this method. I have to enable it to Wifi only, as it will download all of the file as quickly as possible, and exceed the 5MB per 5 minute check they do in app review. I would like to be able to download the mp3 to the app and/or stream it to the app (could create a UIAlertView asking if they want to stream or download) and when enough is downloaded, begin playing immediately, and set it up in a way to not exceed bandwidth over cellular usage. What would be my best way to download the mp3 when selecting an episode, set limits on bandwidth, and begin playing when enough is downloaded?