accessing inherited array in Objective C - objective-c

Question

I'm currently working on a project that's split in two classes, the class 'Array' and the class 'PPCalcVals'. Because other classes, that will be added, will also have to have access the array, I thought it would be the best to write the array class, containing an NSMutableArray and Subclass all the others (beginning with the PPCalcVals class.
So the 'PPCalcVals' class needs to access the elements of the array in the superclass 'Array'.
(Please correct me if this is the wrong approach).
As mentioned the whole program is written and well working in C but to create a GUI and eventually an OSX or IOS application I started to learn OOProgramming with Objecitve C.
Anyways, when I reference the objects in the array of the superclass the only value that gets printed is "null" which is not really what I want.
Here is the code:
main routine:
#import <Foundation/Foundation.h>
#import "Array.h"
#import "PPCalcVals.h"
int main(int argc, const char * argv[])
{
#autoreleasepool
{
Array *prices = [[Array alloc]initWithName:#0];
PPCalcVals *myVals = [[PPCalcVals alloc]init];
[prices addValue:#12];
[prices addValue:#13];
[prices addValue:#14];
[prices addValue:#15];
[prices addValue:#15];
[prices print];
[myVals print];
}
return 0;
}
array.h file:
#import <Foundation/Foundation.h>
#interface Array : NSObject
{
NSMutableArray *prices;
}
-(id) initWithName: (NSNumber *) values;
-(void) addValue: (NSNumber *) value;
-(void) print;
-(NSMutableArray *) prices;
#end
array.m
#import "Array.h"
#implementation Array
-(id) initWithName:(NSNumber *)values
{
self = [super init];
if(self)
{
prices = [NSMutableArray array];
}
return self;
}
-(void) addValue: (NSNumber *) value
{
[prices addObject:value];
}
-(void) print
{
NSLog(#"%#",prices);
}
-(NSMutableArray *)prices
{
return prices;
}
#end
PPCalcVals.h:
#import "Array.h"
#interface PPCalcVals : Array
#property id high,low,open,close;
-(void) setHigh:(NSMutableArray *)h setLow:(NSMutableArray *)l; //set high and low
-(void) setOpen:(NSMutableArray *)o setClose:(NSMutableArray *)c; //set open and close
-(void) sort; //sort array
-(void) print; //debugging tool
#end
PPCalcVals.m:
#import "PPCalcVals.h"
#implementation PPCalcVals
#synthesize high,low,open,close;
-(void) setOpen:(NSMutableArray *)o setClose:(NSMutableArray *)c
{
o = prices[0];
c = prices[2];
open = o;
close = c;
}
-(void) sort;
{
[prices sortedArrayUsingComparator:^(NSString *str1, NSString *str2) {
return [str1 compare:str2 options:NSNumericSearch];
}];
}
-(void) setHigh:(NSMutableArray *)h setLow:(NSMutableArray *)
{
h = prices[0];
l = prices[2];
high = h;
low = l;
}
-(void) print
{
NSLog(#"open: %#",open);
NSLog(#"close: %#",close);
NSLog(#"high: %#",high);
NSLog(#"low: %#",low);
}
#end
The running program outputs only:
2013-08-05 10:21:08.546 prog1[1314:303] (
12,
13,
14,
15,
15
)
open: (null)
close: (null)
high: (null)
low: (null)
I realize that this is probably a really basic question but I would appreciate your help a lot and I already thank you if you read until this point ;)

Answer 1

You have created two distinct, completely unrelated objects prices and myVals:
Array *prices = [[Array alloc]initWithName:#0];
PPCalcVals *myVals = [[PPCalcVals alloc]init];
What you probably meant is to create a PPCalcVals object (which inherits
all methods from the superclass Array):
PPCalcVals *prices = [[PPCalcVals alloc]init];
[prices addValue:#12]; // invokes `addValue` method from superclass "Array"
// ...
[prices print]; // invokes `print` method from "PPCalcVals"
You also have to implement init in the PPCalcVals class in such a way
that it calls the "designated initializer" initWithName in the superclass.

Answer 2

I have one question. Where did you make calls for the functions
-(void) setHigh:(NSMutableArray *)h setLow:(NSMutableArray *)l;
-(void) setOpen:(NSMutableArray *)o setClose:(NSMutableArray *)c;
Because all I can see is that these functions are not called. So the properties high, low, open & close are not yet assigned and thus they return Null.
Also may I know the reason why are you overriding the parameters inside above mentioned functions?
o = prices[0];
c = prices[2];
and
h = prices[0];
l = prices[2];