Twitter's statuses/update_with_media on iOS re

Does anybody use new twitter functionality, statuses/update_with_media?
I've tried to use it to upload photo and it returns internal server error.
My request is following:

*********************** start of request *************************
POST /1/statuses/update_with_media.json HTTP/1.1
Host: upload.twitter.com
User-Agent: CGJ/0.9.7 CFNetwork/485.13.8 Darwin/10.6.0
X-Twitter-Client: MGTwitterEngine
X-Twitter-Client-Version: 1.0
X-Twitter-Client-Url: http://mattgemmell.com/source
Content-Type: multipart/form-data; boundary=--------Asrf456BGe4h
Authorization: OAuth realm="", oauth_consumer_key="wEmJfFrYHMgmCGjAzHdS7Q", oauth_token="366466306-U2RDh7faJtMyi39ALIo2PooaKNT6BxHVT23UUVe4", oauth_signature_method="HMAC-SHA1", oauth_signature="Ev2RxuZbk3DiTQryIDUTPIJxYYE%3D", oauth_timestamp="1315289679", oauth_nonce="A968261D-CB8A-4E07-87AD-47AB138D332D", oauth_version="1.0", oauth_verifier="0087890"
Accept: */*
Accept-Language: en-us
Accept-Encoding: gzip, deflate
Content-Length: 4528
Connection: keep-alive

----------Asrf456BGe4h
Content-Disposition: form-data; name="status"

Test image uploading
----------Asrf456BGe4h
Content-Disposition: form-data; name="media[]"; filename="1.png"
Content-Type: image/png

iVBORw0... - base64 image data
----------Asrf456BGe4h
*********************** end of request *************************

I'm using MGTwitterEngine and here is the code that generate this request:

- (NSString *) _uploadImage:(UIImage *)image requestType:(MGTwitterRequestType)requestType responseType:(MGTwitterResponseType)responseType
{
  NSString *boundary = @"--------Asrf456BGe4h";

  NSURL *finalURL = [NSURL     URLWithString:@"http://upload.twitter.com/1/statuses/update_with_media.json"];
  if (!finalURL) {
    return nil;
  }

  OAMutableURLRequest *theRequest = [[[OAMutableURLRequest alloc] initWithURL:finalURL
                                                                 consumer:self.consumer 
                                                                    token:_accessToken 
                                                                    realm: nil
                                                        signatureProvider:nil] autorelease];
  [theRequest setHTTPMethod:@"POST"];
  [theRequest setHTTPShouldHandleCookies:NO];

  // Set headers for client information, for tracking purposes at Twitter.
  [theRequest setValue:_clientName    forHTTPHeaderField:@"X-Twitter-Client"];
  [theRequest setValue:_clientVersion forHTTPHeaderField:@"X-Twitter-Client-Version"];
  [theRequest setValue:_clientURL     forHTTPHeaderField:@"X-Twitter-Client-URL"];

  NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary];
  [theRequest setValue:contentType forHTTPHeaderField:@"content-type"];

  // Set request body, if specified (hopefully so), with 'source' parameter if appropriate.

  NSMutableData *body = [NSMutableData dataWithLength:0];
  [body appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"status\"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithString:@"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithString:@"Honeymoon application uploads image\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];

  [body appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"media[]\"; filename=\"1.png\"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithString:@"Content-Type: image/png\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithString:@"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];  
  [body appendData:[[NSString stringWithString:[UIImagePNGRepresentation(image) base64EncodingWithLineLength:0]] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithString:@"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithFormat:@"--%@", boundary] dataUsingEncoding:NSUTF8StringEncoding]];

  [theRequest setHTTPBody:body];

  [theRequest prepare];

  MGTwitterHTTPURLConnection *connection;
  connection = [[MGTwitterHTTPURLConnection alloc] initWithRequest:theRequest 
                                                      delegate:self 
                                                   requestType:requestType 
                                                  responseType:responseType];

  if (!connection) {
    return nil;
  } else {
    [_connections setObject:connection forKey:[connection identifier]];
    [connection release];
  }

  return [connection identifier];  
}

Can anybody help me to detect what is wrong?
Thanks in advance!

I've solved the problem, but really I don't know where root cause was.
So, what was done is changing the code in following manner:

- (NSString *) _uploadImage:(UIImage *)image requestType:(MGTwitterRequestType)requestType responseType:(MGTwitterResponseType)responseType
{

  NSString *boundary = @"----------------------------991990ee82f7";

  NSURL *finalURL = [NSURL URLWithString:@"http://upload.twitter.com/1/statuses/update_with_media.json"];
  if (!finalURL) {
    return nil;
  }


  OAMutableURLRequest *theRequest = [[[OAMutableURLRequest alloc] initWithURL:finalURL
                                                                 consumer:self.consumer 
                                                                    token:_accessToken 
                                                                    realm: nil
                                                        signatureProvider:nil] autorelease];

  [theRequest setHTTPMethod:@"POST"];
  [theRequest setHTTPShouldHandleCookies:NO];

  // Set headers for client information, for tracking purposes at Twitter.
  [theRequest setValue:_clientName    forHTTPHeaderField:@"X-Twitter-Client"];
  [theRequest setValue:_clientVersion forHTTPHeaderField:@"X-Twitter-Client-Version"];
  [theRequest setValue:_clientURL     forHTTPHeaderField:@"X-Twitter-Client-URL"];


  NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary];
  [theRequest setValue:contentType forHTTPHeaderField:@"content-type"];

  NSMutableData *body = [NSMutableData dataWithLength:0];
  [body appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];

  [body appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"media_data[]\"; filename=\"1.png\"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithString:@"Content-Type: application/octet-stream\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithString:@"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];  
  [body appendData:[[NSString stringWithString:[UIImageJPEGRepresentation(image, 1.0) base64EncodingWithLineLength:0]] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"status\"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithString:@"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithString:@"Honeymoon uploads image\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
  [body appendData:[[NSString stringWithFormat:@"--%@--\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];

// --------------------------------------------------------------------------------
// modificaiton from the base clase
// our version "prepares" the oauth url request
// --------------------------------------------------------------------------------
    [theRequest prepare];

  [theRequest setHTTPBody:body];

  // Create a connection using this request, with the default timeout and caching policy, 
  // and appropriate Twitter request and response types for parsing and error reporting.
  MGTwitterHTTPURLConnection *connection;
  connection = [[MGTwitterHTTPURLConnection alloc] initWithRequest:theRequest 
                                                      delegate:self 
                                                   requestType:requestType 
                                                  responseType:responseType];

  if (!connection) {
    return nil;
  } else {
    [_connections setObject:connection forKey:[connection identifier]];
    [connection release];
  }

  return [connection identifier];  
}

There are 3 differences with previous code:
1. Different order of data, it means that firstly image data was filled, and then status data
2. Using media_data[] key instead of media[]
3. Call set http body of request after prepare

Hope it will be helpful for someone.