Posting JSON file using NSURLSession.

gistfile1.m

// URL of the endpoint we're going to contact.
    NSURL *url = [NSURL URLWithString:@"http://localhost:8080/my.json"];

    // Create a simple dictionary with numbers.
    NSDictionary *dictionary = @{ @"numbers" : @[@1, @2, @3] };
    
    // Convert the dictionary into JSON data.
    NSData *JSONData = [NSJSONSerialization dataWithJSONObject:dictionary
                                                       options:0
                                                         error:nil];
    
    // Create a POST request with our JSON as a request body.
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    request.HTTPMethod = @"POST";
    request.HTTPBody = JSONData;
    
    // Create a task.
    NSURLSessionDataTask *task = [[NSURLSession sharedSession] dataTaskWithRequest:request
                                                                 completionHandler:^(NSData *data,
                                                                                     NSURLResponse *response,
                                                                                     NSError *error)
                                  {
                                      if (!error)
                                      {
                                          NSLog(@"Status code: %i", ((NSHTTPURLResponse *)response).statusCode);
                                      }
                                      else
                                      {
                                          NSLog(@"Error: %@", error.localizedDescription);
                                      }
                                  }];
    
    // Start the task.
    [task resume];