Here ya go

gistfile1.txt

- (void)fetchTrainResponseForLine:(NSString *)lineCode
                           origin:(NSString *)originCode
                      destination:(NSString *)destinationCode
                      andCallback:(SGMetraTrainResponseCallback)trainResponseCallback {
    NSURL *metraURL = [NSURL URLWithString:@"http://12.205.200.243/AJAXTrainTracker.svc/GetAcquityTrainData"];
    NSMutableURLRequest *metraRequest = [[NSMutableURLRequest alloc] initWithURL:metraURL];
    
    NSData *requestJson = [[NSString stringWithFormat:@"{\"stationRequest\":{\"Corridor\":\"%@\",\"Destination\":\"%@\",\"Origin\":\"%@\",\"timestamp\":\"/Date(%i-0000)/\"}}", lineCode, destinationCode, originCode, (int)[[NSDate date] timeIntervalSince1970]] dataUsingEncoding:NSUTF8StringEncoding];
    
    [metraRequest setHTTPBody:requestJson];
    [metraRequest setHTTPMethod:@"POST"];
    [metraRequest addValue:@"application/json; charset=UTF-8" forHTTPHeaderField:@"Content-Type"];
    [metraRequest addValue:@"Opera/9.80 (J2ME/MIDP; Opera Mini/9.80 (S60; SymbOS; Opera Mobi/23.348; U; en) Presto/2.5.25 Version/10.54" forHTTPHeaderField:@"User-Agent"];
    
    self.dataTask = [[NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]] dataTaskWithRequest:metraRequest completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        SGMetraTrainResponse *trainResponse = nil;
        if (response) {
            trainResponse = [[SGMetraTrainResponse alloc] initWithTrainResponseJsonData:data];
            dispatch_async(dispatch_get_main_queue(), ^{
                if (trainResponseCallback) {
                    trainResponseCallback(trainResponse, error);
                }
            });
        }
        [self setNetworkActivityIndicatorVisible:NO];
    }];
    [self.dataTask resume];
    [self setNetworkActivityIndicatorVisible:YES];
}