I guess I kinda cheated a little, in that I’d come across properties before elsewhere, so I already knew how to use them to an extent.
Rewriting with proper setters and getters wouldn’t be difficult, just time consuming 
Here’s my solution:
BNRStockHolding.h
[code]#import <Foundation/Foundation.h>
@interface BNRStockHolding : NSObject
@property (nonatomic) float purchaseSharePrice;
@property (nonatomic) float currentSharePrice;
@property (nonatomic) int numberOfShares;
@property (nonatomic) NSString *nameOfStock;
- (float)costInDollars; // purchaseSharePrice * numberOfShares
- (float)valueInDollars; // currentSharePrice * numberOfShares
@end
[/code]
BNRStockHolding.m
[code]#import “BNRStockHolding.h”
@implementation BNRStockHolding
-
(float)costInDollars
{
return _purchaseSharePrice * _numberOfShares;
} -
(float)valueInDollars
{
return _currentSharePrice * _numberOfShares;
}
@end
[/code]
main.m
[code]#import <Foundation/Foundation.h>
#import “BNRStockHolding.h”
int main(int argc, const char * argv[])
{
@autoreleasepool {
BNRStockHolding *csco = [[BNRStockHolding alloc]init];
[csco setNameOfStock:@"CSCO"];
[csco setPurchaseSharePrice:22.57];
[csco setCurrentSharePrice:25.24];
[csco setNumberOfShares:8000];
BNRStockHolding *aapl = [[BNRStockHolding alloc]init];
[aapl setNameOfStock:@"AAPL"];
[aapl setPurchaseSharePrice:83.45];
[aapl setCurrentSharePrice:97.89];
[aapl setNumberOfShares:35];
BNRStockHolding *bbry = [[BNRStockHolding alloc]init];
[bbry setNameOfStock:@"BBRY"];
[bbry setPurchaseSharePrice:12.23];
[bbry setCurrentSharePrice:7.24];
[bbry setNumberOfShares:100];
NSMutableArray *stocks = [[NSMutableArray alloc]init];
[stocks addObject:csco];
[stocks addObject:aapl];
[stocks addObject:bbry];
for (BNRStockHolding *stock in stocks) {
NSLog(@"\n%@ stocks cost %.2f$, now worth %.2f$. Value changed by %.2f$.", stock.nameOfStock, stock.costInDollars, stock.valueInDollars, (stock.valueInDollars - stock.costInDollars));
}
}
return 0;
}
[/code]