title: Downloaded file does not exist
body: <p>I download a file in the background by using <a href="http://code.tutsplus.com/tutorials/ios-7-sdk-background-transfer-service--mobile-20595" rel="nofollow">this tutorial</a></p>
  
  <p>When the file is downloaded, there are 2 functions informing us. I write them in order of time happening:</p>
  
  <p><strong>1)</strong>  <code>- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)downloadURL;</code></p>
  
  <p><strong>2)</strong> <code>- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error;</code></p>
  
  <p>In the function 1, I check the downloaded file still exists.</p>
  
  <p>In the function 2, I check the downloaded file does not exists. I think it is deleted by the iOS system.</p>
  
  <p>Could you explain for me why?
  Thanks</p>