Bad response code when uploading image with Twitpic API

Question

Can anybody familiar with the source code for uploading image to Twitter using "Twitpic api" please tell why I get a 0 response code when I am trying to upload an image?

Here is my code:

- (BOOL)uploadImageToTwitpic:(UIImage*)image
                 withMessage:(NSString*)theMessage
                    username:(NSString*)username
                    password:(NSString*)password
{
    NSString *stringBoundary, *contentType, *message, *baseURLString, *urlString;
    NSData *imageData;
    NSURL *url;
    NSMutableURLRequest *urlRequest;
    NSMutableData *postBody;

    // Create POST request from message, imageData, username and password
    baseURLString = kTwitpicUploadURL;
    urlString = [NSString stringWithFormat:@"%@", baseURLString];
    url = [NSURL URLWithString:urlString];
    urlRequest = [[[NSMutableURLRequest alloc] initWithURL:url] autorelease];
    [urlRequest setHTTPMethod:@"POST"];

    // Set the params
    message = ([theMessage length] > 1) ? theMessage : @"Here's my new Light Table collage.";
    imageData = UIImageJPEGRepresentation(image, kTwitpicImageJPEGCompression);

    // Setup POST body
    stringBoundary = [NSString stringWithString:@"0xKhTmLbOuNdArY"];
    contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", stringBoundary];
    [urlRequest addValue:contentType forHTTPHeaderField:@"Content-Type"];

    // Setting up the POST request's multipart/form-data body
    postBody = [NSMutableData data];
    [postBody appendData:[[NSString stringWithFormat:@"\r\n\r\n--%@\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [postBody appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"source\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
    [postBody appendData:[[NSString stringWithString:@"lighttable"] dataUsingEncoding:NSUTF8StringEncoding]]; // So Light Table show up as source in Twitter post

    [postBody appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [postBody appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"username\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
    [postBody appendData:[[NSString stringWithString:username] dataUsingEncoding:NSUTF8StringEncoding]]; // username

    [postBody appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [postBody appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"password\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
    [postBody appendData:[[NSString stringWithString:password] dataUsingEncoding:NSUTF8StringEncoding]]; // password

    [postBody appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [postBody appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"message\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
    [postBody appendData:[[NSString stringWithString:message] dataUsingEncoding:NSUTF8StringEncoding]]; // message

    [postBody appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [postBody appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"media\"; filename=\"%@\"\r\n", @"lighttable_twitpic_image.jpg" ] dataUsingEncoding:NSUTF8StringEncoding]];
    [postBody appendData:[[NSString stringWithString:@"Content-Type: image/jpg\r\n"] dataUsingEncoding:NSUTF8StringEncoding]]; // jpeg as data
    [postBody appendData:[[NSString stringWithString:@"Content-Transfer-Encoding: binary\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
    [postBody appendData:imageData]; // Tack on the imageData to the end

    [postBody appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n", stringBoundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [urlRequest setHTTPBody:postBody];
    NSLog(@"data=======>%@",postBody);
    NSLog(@"URLReq========>%@",urlRequest);
    // Spawn a new thread so the UI isn't blocked while we're uploading the image
    [NSThread detachNewThreadSelector:@selector(uploadingDataWithURLRequest:) toTarget:self withObject:urlRequest];

    return YES; // TODO: Should raise exception on error
}

- (void)uploadingDataWithURLRequest:(NSURLRequest*)urlRequest {
    // Called on a separate thread; upload and handle server response

    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    [urlRequest retain]; // Retain since we autoreleased it before

    // Send the request
    NSHTTPURLResponse *urlResponse;
    NSError *error;
    NSData *responseData = [NSURLConnection sendSynchronousRequest:urlRequest
                                                 returningResponse:&urlResponse
                                                             error:&error];
    NSString *responseString = [[NSString alloc] initWithData:responseData
                                                     encoding:NSUTF8StringEncoding];

    // Handle the error or success
    // If error, create error message and throw up UIAlertView
    NSLog(@"Response Code: %d", [urlResponse statusCode]);
    if ([urlResponse statusCode] >= 200 && [urlResponse statusCode] < 300) {
        NSLog(@"urlResultString: %@", responseString);

        NSString *match = [responseString stringByMatching:@"http[a-zA-Z0-9.:/]*"]; // Match the URL for the twitpic.com post
        NSLog(@"match: %@", match);

        // Send back notice to delegate
        [delegate twitpicEngine:self didUploadImageWithResponse:match];
    }
    else {
        NSLog(@"Error while uploading, got 400 error back or no response at all: %@", [urlResponse statusCode]);
        [delegate twitpicEngine:self didUploadImageWithResponse:nil]; // Nil should mean "upload failed" to the delegate
    }

    [pool drain];
    [responseString release];
    [urlRequest release];
}