-[NSConcreteMutableData release]: message sent to deallocated instance - instance

Question

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; 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

Answer 1

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

Answer 2

NSMutableData *body = [[NSMutableData data] autorelease];
remove that autorelease message