GCDAsyncSocket delegate. This shows how to queue a read in AsyncSocket.

SocketServerDelegate.m

// GCDAsyncSocket delegate, this occurs when the server has sent the message asking the client to send JSON
- (void)socket:(GCDAsyncSocket *)sock didWriteDataWithTag:(long)tag
{
    if (tag == TAG_ASK_FOR_JSON) {
        NSLog(@"didWriteDataWithTag tag (TAG_ASK_FOR_JSON) in SocketServerDelegate.m - First Request sent from server to device sending JSON, asking it to send JSON data");

        // Now start the queue to read in the JSON stream from the client
        [sock readDataToData:[GCDAsyncSocket CRLFData] withTimeout:-1 tag:TAG_READ_JSON_DATA]; // parse all the way to CRLF
        
        // You can even specify what should be used as a terminator for a byte stream
        //NSData *term = [@"\r\n\r\n" dataUsingEncoding:NSUTF8StringEncoding];
        //[socket readDataToData:term withTimeout:-1 tag:HTTP_HEADER];
    }
}