Post data in Objective C using Json

I am trying to post data to a PHP web service.
I am familiar doing this in html using query $.post but I am very much stumped trying this in objective C. I tried several blogs & questions found on stackoverflow.

I finally came up with the following code:

NSString *jsonRequest = [NSString stringWithFormat:@"{\"Email\":\"%@\",\"FirstName\":\"%@\"}",user,fname];
NSLog(@"Request: %@", jsonRequest);

NSURL *url = [NSURL URLWithString:@"http:myurl..."];

NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url];
NSData *requestData = [NSData dataWithBytes:[jsonRequest UTF8String] length:[jsonRequest length]];

[request setHTTPMethod:@"POST"];
[request setValue:@"application/json" forHTTPHeaderField:@"Accept"];
[request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
[request setValue:[NSString stringWithFormat:@"%d", [requestData length]] forHTTPHeaderField:@"Content-Length"];
[request setHTTPBody: requestData];

NSURLConnection *connection = [NSURLConnection connectionWithRequest:request delegate:self];

I also tried:
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];

My web service creates a new user on post and returns the userID. Both successfully make the web service call(a new userID is created), however they do not post the data, i.e. a blank user is created every time.
Please tell me if I am missing anything.

Thanks.

My other attempts:

NSMutableURLRequest *request = 
[[NSMutableURLRequest alloc] initWithURL:
 [NSURL URLWithString:@"myUrl.. "]];

[request setHTTPMethod:@"POST"];

NSString *postString = @"Email=me@test.com&FirstName=Test";

[request setValue:[NSString 
                   stringWithFormat:@"%d", [postString length]] 
forHTTPHeaderField:@"Content-length"];

[request setHTTPBody:[postString 
                      dataUsingEncoding:NSUTF8StringEncoding]];

[[NSURLConn