title: Return custom NSURLResponse class
body: <p>I try to return an object of a subclass of NSURLResponse in my custom NSURLProtocol, but it seems the returned response is always exchanged by a normal NSURLResponse.</p>
  
  <p>This is the part of the NSURLProtocol where I return my custom TestURLResponse:</p>
  
  <pre><code>TestURLResponse* response = [[[TestURLResponse alloc] initWithURL: [[self request] URL]
                                                          MIMEType: @"text/plain" 
                                             expectedContentLength: 4
                                                  textEncodingName:@"UTF-8"]
                               autorelease];
  [self.client URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed];
  [self.client URLProtocol:self didLoadData: [@"Test" dataUsingEncoding:NSUTF8StringEncoding]];
  [self.client URLProtocolDidFinishLoading: self];
  </code></pre>
  
  <p>When I read something with this protocol I expect to get the response of type TestURLResponse, but in the following code I always get a NSURLResponse:</p>
  
  <pre><code>    NSURLRequest* request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"test://test"]];
  NSURLResponse* response;
  [NSURLConnection sendSynchronousRequest:request returningResponse:&amp;response error:nil];
  
  NSString *className = NSStringFromClass([response class]);
  
  UIAlertView* alertView = [[UIAlertView alloc] initWithTitle:className  message:className delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
  [alertView show];
  [alertView release];
  </code></pre>
  
  <p>The whole test project can be downloaded at </p>
  
  <p><a href="http://ul.to/9yylk65s">http://ul.to/9yylk65s</a></p>
  
  <p>Right now I have no idea if I'm doing something wrong or if there is something broken. The documentation of NSURLProtocol states</p>
  
  <blockquote>
    <p>A protocol implementor may wish to create a custom, mutable NSURLResponse class to provide protocol specific information.</p>
  </blockquote>
  
  <p>but it seems to me, this isn't working at all.</p>