iPhone in-app file download

I have a tour guide app that can play audio tours in addition to displaying the text. Right now the mp3 audio is installed with the app which makes the app size large. I need the mp3 files to be downloaded after the app is installed in order to make the app size small. I need some class files that I could add into my project to accomplish the following. When the app is started it should check the given XML file for a list of necessary mp3 files with http download links. If not all were downloaded, Ask the user to start download. When a user clicks on a tour guide, when it loads it will check if the audio file is present. If it's not available, ask to start download. As the user to download by displaying "Would you like to download the audio to listen to the tour? (About 5min with WiFi)". If the user presses YES, check if WiFi is enabled. If not, display "wifi is required to download due to heavy bandwidth requirements". The downloader will use the links from the given XML to download all the for the app MP3s (not just the current tour). Display a progress bar Indicating that the download is active with "N of X guides downloaded." A Pause Download button lets the download be resumed later. Also, if the user exists the app during download, when the user returns to the app, it should be able to tell if there are still tours that should be downloaded. So the functions I need are summarized here: - check if some tours still need to be downloaded - check if wifi is available - download the tours It should work on OS 3+. Let me know if you have any questions.