-[NSConcreteMutableData release]: message sent to deallocated instance

I am facing a problem of -[NSConcreteMutableData release]: message sent to deallocated instance, i have attached my sample code as well.

- (IBAction)uploadImage {

NSString *urlString = @"http://192.168.1.108/iphoneimages/uploadfile.php?userid=1&charid=23&msgid=3";


//if(FALSE)
for (int i=0开发者_开发问答; i<[imgArray count]; i++) {

    // setting up the request object now
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
    [request setURL:[NSURL URLWithString:urlString]];
    [request setHTTPMethod:@"POST"];

    /*
    add some header info now
    we always need a boundary when we post a file
    also we need to set the content type

    You might want to generate a random boundary.. this is just the same 
    as my output from wireshark on a valid html post
 */
    NSString *boundary = [NSString stringWithString:@"---------------------------14737809831466499882746641449"];
    NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@",boundary];
    [request addValue:contentType forHTTPHeaderField: @"Content-Type"];

    /*
     now lets create the body of the post
     */
    NSMutableData *body = [[NSMutableData data] autorelease];

    NSString *str = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"userfile\"; filename=\"ipodfile%d.jpg\"\r\n",i];

    [body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];    
    [body appendData:[[NSString stringWithString:str] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithString:@"Content-Type: application/octet-stream\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];


    NSData *imageData = UIImageJPEGRepresentation([imgArray objectAtIndex:i], 90);
    [body appendData:[NSData dataWithData:imageData]];


    [body appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    // setting the body of the post to the reqeust
    [request setHTTPBody:body];

    // now lets make the connection to the web
    [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
    //NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];
    //NSLog(@"%@",returnString);
    [imageData release];

    [request release];
    //[body release];
}
}

It successfully upload the images to the folder and there is no any error in the execution but when it complete it process and try to go back it give error -[NSConcreteMutableData release]: message sent to deallocated instance

Please help me out.

Thanks

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UIImageJPEGRepresentation returns an auto released object and you release it. When this is auto released it will blow up.

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NSMutableData *body = [[NSMutableData data] autorelease];

remove that autorelease message