title: RestKit object mapping request that has nested JSON in its HTTP body
body: <p>I am making a POST request with a nested JSON in its HTTP body and I am not getting the appropriate response. I am passing a custom object called RequestObject with properties:</p>
  
  <pre><code>@interface RequestObject : NSObject
  @property (nonatomic, copy) NSString *title;
  @property (nonatomic, strong) NSDictionary *location;
  @property (nonatomic, strong) NSMutableArray *pictures;
  </code></pre>
  
  <p>I want to map my object such that in its HTTP Body, the JSON would look like this:</p>
  
  <pre><code>{
          "title": "Magic School Bus",
          "location": {
              "latitude": "38.764792",
              "longitude": "-121.247574"
          },
          "pictures": [
              {
                  "base64pic": "iVBORw0KGg..."
              }
          ]
  }
  </code></pre>
  
  <p>For the request object, I configured it like so:</p>
  
  <pre><code>RequestObject *request = [[RequestObject alloc] init];
  
  // Title property
  request.title = @"MyTitle";
  
  // Location property
  request.location = @{
                @"latitude" : [NSNumber numberWithDouble:38.757965],
                @"longitude" : [NSNumber numberWithDouble:-121.254044]
                };
  
  // Pictures property
  request.pictures = [[NSMutableArray alloc] init]; 
  
  // I add a dictionary into the pictures array
  NSDictionary *picture = @{@"base64pic" : @"somebase64string"};
  [request.pictures addObject:picture];
  </code></pre>
  
  <p>I believe I may be setting my request.pictures incorrectly and that is why my response comes back wrong. This is the rest of my code for calling the POST request:</p>
  
  <pre><code>RKObjectMapping *requestMapping = [RKObjectMapping requestMapping];
  [mapping addAttributeMappingsFromArray:@[@"title", @"location", @"pictures"]];
  [manager addRequestDescriptor:[RKRequestDescriptor requestDescriptorWithMapping:requestMapping objectClass:[RequestObject class] rootKeyPath:nil method:RKRequestMethodPOST]];
  
  RKObjectMapping *responseMapping = [RKObjectMapping mappingForClass:[NSDictionary class]];
  [mapping addAttributeMappingsFromArray:@[@"response"]];
  [manager addResponseDescriptor:[RKResponseDescriptor responseDescriptorWithMapping:responseMapping method:RKRequestMethodPOST pathPattern:nil keyPath:nil statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
  
  // Post
  [manager postObject:request path:@"books/" parameters:nil success:^(RKObjectRequestOperation *operation, RKMappingResult *result){
  
      // Response back
  }failure:^(RKObjectRequestOperation *operation, NSError *error) {
  </code></pre>
  
  <p>When I make the POST call in my project, I see this as the HTTP Request body in my console:</p>
  
  <pre><code>Request Body : location[latitude]=38.757965&amp;location[longitude]=-121.254044&amp;pictures[][base64pic]=somebase64string&amp;title=MyTitle
  </code></pre>