How to use NSURLRequest / NSURLConnection to download an mp3 file to app?

The Situation

In my app, I am currently downloading an mp3 file (to docs directory) using [NSData dataWithContentsOfURL:URL], a method that works fine, but ties down the CPU, dissallowing screen updates of download status. So, I want to download usi开发者_如何学编程ng a different method so that I can update the screen WHILE downloading to alert the user that the download has begun.

Question

How do I set up my viewController to use NSURLRequest or NSURLConnection to download an mp3 file? (please give source)

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Use "NSURLConnection asynchronously" search for the term and you'll find source. Or just NSURLConnection.

For example:

NSURLConnection NSURLRequest proxy for asynchronous web service calls