ResKit Object Mapping nested objects - ios

Question

I am attempting to use RestKit to parse some JSON. The app is for tracking competitions, and has a concept of venues, games, and players. A game has a winner and loser (both of class Player) and a venue. The JSON returned by the web service looks like this:
[{"id":1,"winner":{"name":"NAME2","id":2,"picture_url":"CK.png"},"loser":{"name":"NAME3","id":3,"picture_url":"NJ.png"},"venue":{"name":"Venue 1","id":2}},
{"id":2,"winner":{"name":"NAME2","id":2,"picture_url":"CK.png"},"loser":{"name":"NAME1","id":1,"picture_url":"NC.png"},"venue":{"name":"Venue 1","id":2}},
{"id":3,"winner":{"name":"NAME2","id":2,"picture_url":"CK.png"},"loser":{"name":"NAME3","id":3,"picture_url":"NJ.png"},"venue":{"name":"Venue 1","id":2}},
{"id":4,"winner":{"name":"NAME2","id":2,"picture_url":"CK.png"},"loser":{"name":"NAME1","id":1,"picture_url":"NC.png"},"venue":{"name":"Venue 1","id":2}}]
My object header files look like this:
# PTGame.h
#interface PTGame : NSObject
#property (nonatomic, assign) NSNumber *uid;
#property (nonatomic, assign) PTPlayer *winner;
#property (nonatomic, assign) PTPlayer *loser;
#property (nonatomic, assign) PTVenue *venue;
#end
# PTVenue.h
#interface PTVenue : NSObject
#property (nonatomic, copy) NSString *name;
#property (nonatomic, assign) NSNumber *uid;
-(CLLocation *)location;
-(CLLocationDistance)distanceFromLocation:(CLLocation *)location;
#end
# PTPlayer.h
#interface PTPlayer : NSObject
#property (nonatomic, copy) NSString *name;
#property (nonatomic, copy) NSString *pictureUrl;
#property (nonatomic, assign) NSNumber *uid;
#end
Finally, my mapping setup looks like:
RKObjectManager *objectManager = [[RKObjectManager alloc] initWithHTTPClient:client];
RKObjectMapping *venueMapping = [RKObjectMapping mappingForClass:[PTVenue class]];
[venueMapping addAttributeMappingsFromDictionary:#{#"name" : #"name",
#"id" : #"uid"}];
RKObjectMapping *playerMapping = [RKObjectMapping mappingForClass:[PTPlayer class]];
[playerMapping addAttributeMappingsFromDictionary:#{#"name" : #"name",
#"id" : #"uid",
#"picture_url": #"pictureUrl"}];
// Add Object Mapping for PTGame
RKObjectMapping *gameResponseMapping = [RKObjectMapping mappingForClass:[PTGame class]];
// Setup Game Object relationships
[gameResponseMapping addAttributeMappingsFromDictionary:#{#"id": #"uid"}];
[gameResponseMapping addRelationshipMappingWithSourceKeyPath:#"winner" mapping:playerMapping];
[gameResponseMapping addRelationshipMappingWithSourceKeyPath:#"loser" mapping:playerMapping];
[gameResponseMapping addRelationshipMappingWithSourceKeyPath:#"venue" mapping:venueMapping];
NSIndexSet *statusCodes = RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful);
RKResponseDescriptor *gameListResponseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:gameResponseMapping
method:RKRequestMethodGET
pathPattern:#"/games.json"
keyPath:nil
statusCodes:statusCodes];
[objectManager addResponseDescriptor:gameListResponseDescriptor];
This all looks right to me. No errors are thrown when the result is returned, but later I get an exception when attempting to access a property of the game. A peek into the objects via XCode debugger shows this:
Something seems to be broken - why do those strings show as "winner" and "venue". Why is the uid null? The objects seem different every time I make the request, leading me to believe the memory is not be handled properly.
Any ideas?

Answer 1

Wain's comment led me down the path of looking outside of the mapping code. I looked in the RestKit Object Mapping docs and noticed all of the attributes were using the nonatomic and copy properties, rather than assign. Additionally, the object references (such as PTPlayer *winner were simply nonatomic. Changing my code to reflect this fixed the issue.
The resulting header files look like:
# PTPlayer.h
#interface PTPlayer : NSObject
#property (nonatomic, copy) NSString *name;
#property (nonatomic, copy) NSString *pictureUrl;
#property (nonatomic, copy) NSNumber *uid;
#end
# PTVenue.h
#interface PTVenue : NSObject
#property (nonatomic, copy) NSString *name;
#property (nonatomic, copy) NSNumber *uid;
#property (nonatomic, assign) CGFloat longitude;
#property (nonatomic, assign) CGFloat latitude;
-(CLLocation *)location;
-(CLLocationDistance)distanceFromLocation:(CLLocation *)location;
#end
# PTGame.h
#interface PTGame : NSObject
#property (nonatomic, copy) NSNumber *uid;
#property (nonatomic) PTPlayer *winner;
#property (nonatomic) PTPlayer *loser;
#property (nonatomic) PTVenue *venue;
#end