Mm…..
I write a code for download a txt file to my iphone, and used NSURLDownload class, it was working very well on simulator, until test the code on Device,
Apple iphone has compiler error
“error: NSURLDownload undeclared”

same code can working on Simulator , but not device.

Copied from the iPhone Documentation
“iPhone OS Note: The NSURLDownload class is not available in iPhone OS as downloading directly to the file system is discouraged. Use the NSURLConnection class instead”

addition:
Oct, 29,2008 :
Yes, Used NSURLConnection can do the same function, and working well on iPhone device.