resolving an NSURLErrorCannotOpenFile error

I wrote some code to download a URL to my disk, using an NSURLRequest and an NSURLDownload. The download starts fine (at least, it sends downloadDidBegin:(NSURLDownload *)download), but then it sends

-(void)download:(NSURLDownload *)download didFailWithError:(NSError *)error

My implementation of the function is as follows:

{
[download release];

NSLog(@"Download failed! Error - %@ %@",
      [error localizedDescription],
      [[error userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]);
}

The logged error is

2011-07-17 01:48:43.194 URLDownloader[28031:903] Download failed! Error - The operation couldn’t be completed. (NSURLErrorDomain error -3001.) [the URL in the NSURLRequest]

From what I can tell, this is the NSURLErrorCannotOpenFile error. I cannot find any explanation of why t开发者_StackOverflow中文版his error occurs, other then "Returned when NSURLDownload was unable to open the downloaded file on disk." from the documentation. So, why is this happening?

Fact that might be helpful(?): NSURLErrorCannotOpenFile is enumerated as kCFURLErrorCannotOpenFile. I have no idea what this means either....

Alright, so I was just being foolish. I had created a path using NSURL's absoluteString method instead of the path method. This was just bad coding on my part...