How to use data from main.m in a subclass - objective-c

Question

I am doing homework from the Big Nerd Ranch Guide book. In the problem, I have two arrays in main.m. One is from a subclass and the other from a superclass. BNRItem is the superclass. BNRContainer is the subclass. In the implementation files I have description string which says what the NSLog should say. I need to take the data from the superclass used in main.m's array and use it in the subclass so that the subclass array can work. is there an easy answer?
In main.m I have the following:
// main.m
// RandomItems
#import <Foundation/Foundation.h>
#import "BNRItem.h"
#import "BNRContainer.h"
int main(int argc, const char * argv[])
{
#autoreleasepool {
NSMutableArray *items = [[NSMutableArray alloc] init];
for (int i = 0; i < 3; i++) {
BNRItem *item = [BNRItem randomItem];
[items addObject:item];
}
for (BNRItem *item in items) {
NSLog(#"%#", item);
}
NSMutableArray *containers = [[NSMutableArray alloc] init];
for (int i = 0; i < 3; i++) {
BNRContainer *container = [BNRContainer randomContainer];
[containers addObject:container];
}
for (BNRContainer *container in containers) {
NSLog(#"%#", container);
}
items = nil;
containers = nil;
}
return 0;
}
In BNRItem.h:
// BNRItem.h
// RandomItems
//
// Created by Meghan on 3/19/14.
// Copyright (c) 2014 Meghan. All rights reserved.
//
#import <Foundation/Foundation.h>
#interface BNRItem : NSObject
{
NSString *_itemName;
NSString *_serialNumber;
int _valueInDollars;
NSDate *_dateCreated;
}
+ (instancetype)randomItem;
//Designated initializer for BNRItem
- (instancetype)initWithItemName:(NSString *)name
valueInDollars:(int)value
serialNumber:(NSString *)sNumber;
-(instancetype)initWithItemName:(NSString *)name;
- (NSString *)description;
- (void)setItemName:(NSString *)str;
-( NSString *)itemName;
- (void)setSerialNumber:(NSString *)str;
- (NSString *)serialNumber;
- (void)setValueInDollars:(int)v;
- (int)valueInDollars;
- (NSDate *)dateCreated;
#end
in BNRContainer.h:
// BNRContainer.h
// RandomItems
//
// Created by Meghan on 3/20/14.
// Copyright (c) 2014 Meghan. All rights reserved.
//
#import "BNRItem.h"
#interface BNRContainer : BNRItem
{
NSString *_containerName;
int _containerItemsSum;
int _containerValue;
int _totalContainerValue;
}
- (NSString *)description;
+ (instancetype)randomContainer;
//Designated initializer for BNRContainer
- (instancetype)initWithContainerName:(NSString *)name
containerItemsSum:(int)iSum
containerValue:(int)value
totalContainerValue:(int)tvalue;
- (instancetype)initWithContainerName:(NSString *)name;
- (instancetype)init;
- (void)setContainerName:(NSString *)str;
- (NSString *)containerName;
- (void)setContainerItemsSum:(int)v;
- (int)containerItemsSum;
- (void)setContainerValue:(int)v;
- (int)containerValue;
- (void)setTotalContainerValue:(int)v;
- (int)totalContainerValue;
#end
The variable containerItemsSum in BNRContainer should be the sum of valueInDollars of several items and the value is generated in main.m when it is looped through.
// BNRItem.m
// RandomItems
//
// Created by Meghan on 3/19/14.
// Copyright (c) 2014 Meghan. All rights reserved.
//
#import "BNRItem.h"
#implementation BNRItem
- (instancetype)initWithItemName:(NSString *)name
valueInDollars:(int)value
serialNumber:(NSString *)sNumber
{
self = [super init];
if (self) {
//Give the instance variables initial values
_itemName = name;
_serialNumber = sNumber;
_valueInDollars = value;
//Set dateCreated to the current date and time
_dateCreated = [[NSDate alloc]init];
}
return self;
}
-(instancetype)initWithItemName:(NSString *)name
{
return [self initWithItemName:name
valueInDollars:0
serialNumber:#""];
}
- (instancetype)init
{
return [self initWithItemName:#"Item"];
}
+ (instancetype)randomItem
{
NSArray *randomAdjectiveList = #[#"Fluffy", #"Rusty", #"Shiny"];
NSArray *randomNounList = #[#"Bear", #"Spork", #"Mac"];
NSInteger adjectiveIndex = arc4random() % [randomAdjectiveList count];
NSInteger nounIndex = arc4random() % [randomNounList count];
NSString *randomName = [NSString stringWithFormat:#"%# %#",
randomAdjectiveList[adjectiveIndex],
randomNounList[nounIndex]];
int randomValue = arc4random() % 100;
NSString *randomSerialNumber = [NSString stringWithFormat:#"%c%c%c%c%c",
'0' + arc4random() % 10,
'A' + arc4random() % 26,
'0' + arc4random() % 10,
'A' + arc4random() % 26,
'0' + arc4random() % 10];
BNRItem *newItem = [[self alloc] initWithItemName:randomName
valueInDollars:randomValue
serialNumber:randomSerialNumber];
return newItem;
}
- (void)setItemName:(NSString *)str
{
_itemName = str;
}
- (NSString *)itemName
{
return _itemName;
}
- (void)setSerialNumber:(NSString *)str
{
_serialNumber = str;
}
- (NSString *)serialNumber
{
return _serialNumber;
}
- (void)setValueInDollars:(int)v
{
_valueInDollars = v;
}
- (int)valueInDollars
{
return _valueInDollars;
}
- (NSDate *)dateCreated
{
return _dateCreated;
}
- (NSString *)description
{
NSString *descriptionString =
[[NSString alloc] initWithFormat:#"%# (%#): Worth $%d, recorded on %#",
self.itemName,
self.serialNumber,
self.valueInDollars,
self.dateCreated];
return descriptionString;
}
#end

Answer 1

for (BNRItem *item in items) {
NSLog(#"%#", item);
}
Here, you're passing through each BNRItem that you've created. This is your opportunity to collect information about the items.
Create a local variable to store the total, and add to it each item you read:
int dollarTotal = 0;
for (BNRItem *item in items) {
NSLog(#"%#", item);
dollarTotal += [item valueInDollars];
}
NSLog(#"Total value in dollars is %d",dollarTotal);
You'd then use this value to set the total for the container, although this seems completely backward. A BNRContainer should (though this may be a later point in the tutorial you are doing) be able to derive this total from its own set of contained items, using a loop similar to the one above. I don't see why you are creating three containers in a loop either. The example doesn't make a great deal of sense.