Error status Code 416 about tcblobdownload

[thibaultcha]

See #31 for more details on the 416 response code and what TCBlobDownload does with the Range header.

[crespoxiao]

@thibaultcha so this problem hasn't been fixed ,right ? maybe the server has some problem.

[jpoag]

I was able to reproduce this error by initializing two (simultaneous) downloads of the same file. This resulted in both downloaders filling the same file on disk (file size is exactly twice the expected size).

Without the user handling the download error by deleting the cache file it will continue to always hit this corrupted file with the wrong size and continuously ask the server for the wrong range.

Also, sometimes the server file will change (such as with Facebook profile image) and the new file will be smaller than old file, also causing 416.

Proposed remedy: Direct the user to always move or remove the download file in the complete handler. Also, don't attempt to download the same file concurrently.

complete:^(BOOL downloadFinished, NSString* pathToFile){
  if(downloadFinished){
    [[NSFileManager defaultManager] removeItemAtPath:theNSLocalPath error:NULL]; // in case is directory
    [[NSFileManager defaultManager] moveItemAtPath:pathToFile toPath:theNSLocalPath error:NULL]; // move to user location
  }
  else{
    [[NSFileManager defaultManager] removeItemAtPath:pathToFile error:NULL]; // remove corrupted download
  }
}