RESTKit: Mapping JSON without mapping class - ios

Question

Below is the JSON response that I get back:
{
"notificationId": 121,
"activities": [
143,
149]
}
Below is the mapping:
RKObjectMapping *mapping = [RKObjectMapping mappingForClass:[NSMutableDictionary class]];
[mapping addAttributeMappingsFromDictionary:#{#"notificationId" : #"notificationId",
#"activities": #"activities"}];
RKResponseDescriptor *responseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:mapping
method:RKRequestMethodGET
pathPattern:nil
keyPath:#""
statusCodes:statusCodeSet];
[self.objectManager postObject:invitation path:#"/notifications" parameters:nil success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
NSString *notificationId1 = [mappingResult.dictionary valueForKey:#"notificationId"];
NSArray *activitesArray1 = [mappingResult.dictionary valueForKey:#"activities"];
NSString *notificationId2 = [mappingResult.dictionary objectForKey:#"notificationId"];
NSArray *activitesArray2 = [mappingResult.dictionary objectForKey:#"activities"];
NSLog(#"notificaiton ID %#", notificationId1);
NSLog(#"Activites %#", activitesArray1);
NSLog(#"notification ID %#", notificationId2);
NSLog(#"Activites %#", activitesArray2);
NSLog(#"Activites Array %#", activitesArray);
NSLog(#"mappingResult Dictionary %#", mappingResult.dictionary);
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
NSLog(#"Failusre");
}];
}
Log:
2014-04-21 19:17:51.273 App[57446:4403] I restkit.network:RKObjectRequestOperation.m:250 POST 'http://www.domain.com/notifications' (200 OK / 1 objects) [request=0.2371s mapping=0.0035s total=0.2446s]
2014-04-21 19:17:51.274 App[57446:60b] notification ID (null)
2014-04-21 19:17:51.274 App[57446:60b] Activites (null)
2014-04-21 19:17:51.274 App[57446:60b] notification ID (null)
2014-04-21 19:17:51.274 App[57446:60b] Activites (null)
2014-04-21 19:17:51.274 App[57446:60b] Activites Array (
)
2014-04-21 19:17:51.275 App[57446:60b] mappingResult Dictionary {
"" = {
activities = (
143,
149
);
notificationId = 121;
};
}
Why are all the values Null? How can I get the values of notificationId back as an NSString and activitiesin an array ? Can this be done without creating a mapping class?

Answer 1

Because your response descriptor is wrong. It should be:
[RKResponseDescriptor responseDescriptorWithMapping:mapping
method:RKRequestMethodPOST
pathPattern:#"/notifications"
keyPath:nil
statusCodes:statusCodeSet];
so that it matches the request you're sending (a POST, not a GET is the main issue).

Answer 2

For some unknow reason, it looks like, there is a wrapper object in the dictionary, that has key value #"" so first extract that and then everything else. Activities itself do look like array, so simply:
NSArray *activities = [[mappingResult.dictionary objectForKey:#""] objectForKey:#"activities"];
However that notification looks tricky, because it probably is a number. So if it is a consistent type, use:
NSNumber *notificationID = [[mappingResult.dictionary objectForKey:#""] objectForKey:#"notificationId"];
NSSring *notificationIDString = [notificationID stringValue];