NSMutableDictionary objects not properly accessed from methods?

Question

I've created an NSMutableDictionary as well as a method to add objects to the dictionary. I know that the function addObject adds objects to the dictionary properly, but later when I try to print the objects using method Print_Object, every single variable belonging to object prints as null/0. Is there something wrong with my code?

-(NSMutableDictionary *)_stock{
    if (!_stock) {
        _stock = [[NSMutableDictionary alloc]init];
    }
    return _stock;  
}

-(void) addObject:(NSString*) desc key: (NSString*) theKey floatrc: (float) retailcost floatwsc: (float) wholesalecost intnoh: (int) numonhand floatns: (int) numsold {
    object_info* obj = [[object_info alloc]init];
    [obj setDescription: desc];
    [obj setRetailCost: retailcost];
    [obj setWholeSaleCost:wholesalecost];
    [obj setNumOnHand: numonhand];
    [obj setNumItemsSold: numsold];
    [self.stock setValue:obj forKey:theKey];   
}

-(void) Print_Object:(NSString *) theKey {
    object_info* obj = [self.stock objectForKey:theKey];
    NSLog(@"Key: %@ Description: %@ Retail Cost: %f Wholesale Cost: %f Number on Hand: %i Number Sold: %i", theKey, obj.description, obj.retail_cost, obj.wholesale_cost, obj.num_on_hand, obj.num_items_sold);     
}

This is the declaration of object_info:

#import "object_info.h"

@implementation object_info

//Getters
-(NSString *)description {
    return description;
}


-(float) retail_cost {
    return retail_cost;
}

-(float) wholesale_cost {
    return wholesale_cost;
}

-(int) num_on_hand {
    return num_on_hand;
}

-(int) num_items_sold {
    return num_items_sold;
}

//Setters
-(void)setDescription:(NSString *) value {
    description = value;
}

-(void) setRetailCost: (float) n {
    retail_cost = n;
}

-(void) setWholeSaleCost: (float) n {
    wholesale_cost = n;
}

-(void) setNumOnHand: (int) n {
    num_on_hand = n;
}

-(void) setNumItemsSold: (int) n {
    num_items_sold = n;
}

@end

This is object_info.h:

#import <Foundation/Foundation.h>

@interface object_info : NSObject
{
    NSString *description;
    float retail_cost;
    float wholesale_cost;
    int num_on_hand;
    int num_items_sold;
}

-(NSString *)description;
-(void)setDescription:(NSString *)value;

-(float) retail_cost;
-(void) setRetailCost:(float) n;

-(float) wholesale_cost;
-(void) setWholeSaleCost:(float) n;

-(int) num_on_hand;
-(void) setNumOnHand: (int) n;

-(int) num_items_sold;
-(void) setNumItemsSold:(int) n;

@end

Answer 1

Can you show us the declaration of stock? I suspect you've declared it as an @property, in which case your attempt to declare -_stock as the getter is going to be ineffective. The instance variable will be _stock but the getter will be just -stock. If this is a correct guess then were you to NSLog(@"%@", self.stock) you should see (null) as the output — your custom getter isn't called so no dictionary is ever created.

Your code generally looks very old fashioned; in particular:

1. you almost never put instance storage inside the @interface now; put it in the @implementation;
2. your entire object_info could be reformulated as @propertys and then you needn't implement a thing inside that @implementation, just allow the properties to auto-synthesise;
3. rather than [obj setDescription: desc];, etc, you'd now more normally see use of dot syntax, like obj.description = desc;. The compiler will still ensure the proper setter (or getter) is called, it's just a formulation that requires less mental context, allowing a direct left-to-right reading;
4. the more normal modern way to access a dictionary is dictionary[key] = value to store and dictionary[key] to access.