Question

As soon as, I send request to the server (via NSURLConnection sendSynchronousRequest method), the server receives it in about 2 seconds, it processes and sends back response in another 3-5 seconds. However, I only get back the response in 30-35 seconds. This delay makes our communication very slow.

Even the async APIs are getting a delayed response.

Earlier, everything was working fine, with client getting the response back within 10 seconds.
Anyone else having this issue? What could be the reason?

EDIT
here is a screenshot of Wireshark analysis:

Link to a better image

How should I see what packet is saying what?..and why is it getting delayed?

EDIT2
Here is the code:

 NSHTTPURLResponse *response=nil;

NSMutableURLRequest *theRequest=[NSMutableURLRequest requestWithURL:[NSURL URLWithString:nsURL] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:180.0];
[theRequest setHTTPMethod:@"POST"];
[theRequest setTimeoutInterval:180.0];
[theRequest setHTTPBody:[[NSString stringWithFormat:@"%@",sdata] dataUsingEncoding:NSASCIIStringEncoding]];

NSError *error= nil;

NSData *result = [NSURLConnection sendSynchronousRequest:theRequest returningResponse:&response error:&error];
if (error ) {
    NSLog(@"error sending synchronous request: %@", error);
}
NSLog(@"request completed with code:%d",response.statusCode);

Answer 1

Solution that worked for me:

In the request headers, iOS sets “gzip” for “Accept-Encoding” by default. The gzip compression was taking a lot of time, and hence the delayed response. I did the following to solve the problem:

[theRequest setValue:@"" forHTTPHeaderField:@"Accept-Encoding"];

NOTE: Check your headers, for any response delay.

Thanks to @occulus for directing me to the request headers!