When I set my downloadProgressBlock for AFNetworking, it is only ever called once at the very end

Question

I'm downloading an image and would like to present some form of progress for the download:

    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:post.url]];
    AFHTTPRequestOperation *imageOperation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
    imageOperation.responseSerializer = [AFImageResponseSerializer serializer];

    [imageOperation setDownloadProgressBlock:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead) {
        NSLog(@"bytesRead: %d, totalBytesRead: %lld, totalBytesExpected: %lld", bytesRead, totalBytesRead, totalBytesExpectedToRead);
    }];

I also have a completion block and [imageOperation start]; after that.

However, if I select an image to download all I ever get logged is:

bytesRead: 72081, totalBytesRead: 72081, totalBytesExpected: 72081

Why is it only giving me the information at the end?

Answer 1

It ended up being due to the fact I had already previously loaded that image, so I assume the OS cached the result. So it only returned 100% progress as it was already downloaded.