iOS: Serialize/Deserialize complex JSON generically from NSObject class

Anyone have idea how to serialize nested JSON based on NSObject class? There is a discussion to serialize simple JSON here , but it is not generic enough to cater complex nested JSON.

Imagine this is the result of JSON:

{ "accounting" : [{ "firstName" : "John",  
                    "lastName"  : "Doe",
                    "age"       : 23 },

                  { "firstName" : "Mary",  
                    "lastName"  : "Smith",
                    "age"       : 32 }
                              ],                            
  "sales"      : [{ "firstName" : "Sally", 
                    "lastName"  : "Green",
                    "age"       : 27 },

                  { "firstName" : "Jim",   
                    "lastName"  : "Galley",
                    "age"       : 41 }
                  ]}

From this class:

@interface Person : NSObject{}
@property (nonatomic, strong) NSString *firstName;
@property (nonatomic, strong) NSString *lastName;
@property (nonatomic, strong) NSNumber *age;
@end

@interface Department : NSObject{}
@property (nonatomic, strong) NSMutableArray *accounting; //contain Person class
@property (nonatomic, strong) NSMutableArray *sales; //contain Person class
@end

How to serialize/deserialize them based on class generically?

EDIT

Currently i'm able to generate payload like this based on any class:

NSMutableDictionary *Payload = [self serialize:objClass];

But it does not cater nested complex JSON. Anyone have better solution for this? This library for C# cater serialize/deserialze based on object class. I want to reproduce something the same based on NSObject