Can't map relationship into array in restkit - ios

Question

So, I have this result from the service:
{
"CustomerPromotions": [
{
"BottomTitle": "Thank you",
"IconURL": "",
"MiddleText": "399$",
"PromotionID": "123B456",
"SortOrder": 0,
"TopTitle": "Welcome to"
}
],
"CustomerStatus": 1,
"CustomerVoucherIcon": "",
"CustomerVoucherText": "",
"CustomerVoucherTitle": "",
"ErrorID": 0,
"ErrorMessage": "",
"FeedbackIndicator": false,
"FeedbackLowerText": "",
"FeedbackTitle": "",
"HPTopTitle": "Hello world",
"LocalCurrencySign": "$",
"LocalCurrencyValue": "3.30",
"LocalTime": "20:30",
"LocalWeather": "-5",
"PopUpTopTitle": ""
}
But for some reason I can't map CustomerPromotions it into an array, this is how my 2 objects looks like:
This is CustomerLogin.h:
#interface CustomerLogin : NSObject
#property (nonatomic) NSArray *customerPromotions;
#property (strong, nonatomic) NSNumber *customerStatus;
#property (strong, nonatomic) NSString *customerVoucherIcon;
#property (strong, nonatomic) NSString *customerVoucherText;
#property (strong, nonatomic) NSString *customerVoucherTitle;
#property (strong, nonatomic) NSNumber *errorID;
#property (strong, nonatomic) NSString *errorMessage;
#property (strong, nonatomic) NSNumber *feedbackIndicator;
#property (strong, nonatomic) NSString *feedbackLowerText;
#property (strong, nonatomic) NSString *feedbackTitle;
#property (strong, nonatomic) NSString *hpTopTitle;
#property (strong, nonatomic) NSString *localCurrencySign;
#property (strong, nonatomic) NSString *localCurrencyValue;
#property (strong, nonatomic) NSString *localTime;
#property (strong, nonatomic) NSString *localWeather;
#property (strong, nonatomic) NSString *popUpTopTitle;
#end
This is 'CustomerPromotions`:
#interface CustomerPromotions : NSObject
#property (strong, nonatomic) NSString *bottomTitle;
#property (strong, nonatomic) NSString *iconURL;
#property (strong, nonatomic) NSString *middleText;
#property (strong, nonatomic) NSString *promotionID;
#property (strong, nonatomic) NSNumber *sortOrder;
#property (strong, nonatomic) NSString *topTitle;
#end
This is the mapping:
RKObjectMapping *customerLoginMapping = [RKObjectMapping mappingForClass:[CustomerLogin class]];
[customerLoginMapping addAttributeMappingsFromDictionary:#{ #"CustomerStatus" : #"customerStatus",
#"CustomerVoucherIcon" : #"customerVoucherIcon",
#"CustomerVoucherText" : #"customerVoucherText",
#"CustomerVoucherTitle" : #"customerVoucherTitle",
#"ErrorID" : #"errorID",
#"ErrorMessage" : #"errorMessage",
#"FeedbackIndicator" : #"feedbackIndicator",
#"FeedbackLowerText" : #"feedbackLowerText",
#"FeedbackTitle" : #"feedbackTitle",
#"HPTopTitle" : #"hpTopTitle",
#"LocalCurrencySign" : #"localCurrencySign",
#"LocalCurrencyValue" : #"localCurrencyValue",
#"LocalTime" : #"localTime",
#"LocalWeather" : #"localWeather",
#"PopUpTopTitle" : #"popUpTopTitle" }];
RKObjectMapping *customerPromotionsMapping = [RKObjectMapping mappingForClass:[CustomerPromotions class]];
[customerPromotionsMapping addAttributeMappingsFromDictionary:#{ #"BottomTitle" : #"bottomTitle",
#"IconURL" : #"iconURL",
#"MiddleText" : #"middleText",
#"PromotionID" : #"promotionID",
#"SortOrder" : #"sortOrder",
#"TopTitle" : #"topTitle" }];
[customerLoginMapping addRelationshipMappingWithSourceKeyPath:#"customerPromotions" mapping:customerPromotionsMapping];
[[RKObjectManager sharedManager] addResponseDescriptor:[RKResponseDescriptor responseDescriptorWithMapping:customerLoginMapping
method:RKRequestMethodPOST
pathPattern:#"CustomerLogin"
keyPath:nil
statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)]];
This is the POST request:
NSDictionary *params = #{ #"AppID" : #"1",
#"AppPassword" : #"String content",
#"Password" : #"password",
#"UserName" : #"username" };
[[RKObjectManager sharedManager] postObject:[[CustomerLogin alloc] init]
path:#"CustomerLogin"
parameters:params
success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
NSLog(#"%#", operation.HTTPRequestOperation.responseString);
NSLog(#"%#", mappingResult.array);
CustomerLogin *customer = [mappingResult.array lastObject];
NSLog(#"%#", customer.customerPromotions);
NSLog(#"%#", customer.hpTopTitle);
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
NSLog(#"%#", error.localizedDescription);
}];

Answer 1

It just looks like your key name is wrong. You use a source key only, which means the source and destination should match but they don't actually match. Try:
RKRelationshipMapping *relationMapping = [RKRelationshipMapping relationshipMappingFromKeyPath:#"CustomerPromotions" toKeyPath:#"customerPromotions" withMapping:customerPromotionsMapping];
[customerLoginMapping addPropertyMapping:relationMapping];