Create MutableArray and add some NSArrays containing Objects - ios

Question

I'm currently learning some objective C but still have problems with the syntax and creating objects.
The Situation: I need a two dimensional "personsArray" which contains many personArrays each containing a NSString *name and a NSNumber *amount (double). Finally I want to calculate some stuff with the array data in another view but I'm far apart from that..
My Plan: Creating a NSMutable Object when the program starts. If I click the Button "Add Person", it creates a personArray with two fixed values (later it should grab those of textAreas). Here is my Code:
Person.h
#import <Foundation/Foundation.h>
#interface Person : NSObject{
NSNumber *amount;
NSString *name;
}
- (void) createPersonArray:(double)theAmount withName:(NSString*) aName;
#end
Person.m
#import "Person.h"
#implementation Person
- (void) createPersonArray:(NSNumber*)theAmount withName:(NSString*) aName{
NSArray* personArray = [NSArray arrayWithObjects:theAmount,aName,nil];
}
#end
ViewController.h
#import <UIKit/UIKit.h>
#interface ViewController : UIViewController
#property (weak,nonatomic) IBOutlet NSMutableArray *personsArray;
- (IBAction)addPerson:(id)sender;
#end
ViewController.m
#import "ViewController.h"
#import "Person.h"
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
}
- (IBAction)addPerson:(id)sender {
Person *newPerson;
newPerson = [Person new];
[newPerson createPersonArray:100.00 withName:#"test"];
[_personsArray addObject:newPerson];
}
#end
I know that this wont work, but I don't know how to realize the stuff that I described above. If I build the program, the app starts. if I click the button the debugger jumps to the createPersonArray and outputs "Thread 1: EXC_BAD_ACCESS (code=1,address=0x40590000] and "Unused variable 'personArray'".
I watched many tutorials know but none of them explained this situation.. How must my code be structured to accomplish my goal? Am I on the right path or is it the wrong approach?
greetings

Answer 1

I think if you want save array to MutableArray, you only need create method in ViewController. If you create Person.h, i suggest you should save to MutableArray is Person Object. You can use code below:
Person.h:
#property (nonatomic, strong) NSNumber *amount;
#property (nonatomic, strong) NSString *name;
instead:
NSNumber *amount;
NSString *name;
Person.m:
#implementation Person
#synthesize name;
#synthesize amount;
- (void) createPersonArray:(double)theAmount withName:(NSString*) aName{
amount = [NSNumber numberWithDouble:theAmount];
name = aName;
}
ViewController.h
#property (strong,nonatomic) NSMutableArray *personsArray;
ViewController.m
- (void)viewDidLoad
{
[super viewDidLoad];
_personsArray = [[NSMutableArray alloc]init];
}
- (IBAction)addPerson:(id)sender {
Person *newPerson;
newPerson = [Person new];
[newPerson createPersonArray:100.00 withName:#"test"];
[_personsArray addObject:newPerson];
}
If you don't understand. You can comment below, i will help you.
When you need get contain, you can use:
for (Person *person in _personsArray){
NSLog(#"Amount: %# \n Name: %# \n ",ps.amount,ps.name,);
}
or
for (int i = 0; i< [_personsArray count]; i++){
Person *ps = [_personsArray objectAtIndex:i];
NSLog(#"Amount: %# - Name:%#",ps.amount,ps.name);
}
================================== UPDATE ===========================
double sumAmount = 0;
for (int i = 0; i < [_personsArray count]; i++){
Person *person = [_personsArray objectAtIndex:i];
sumAmount = sumAmount + [person.amount doubleValue];
}
double averageAmount = sumAmount / [_personsArray count];
NSLog(#"%f",averageAmount);

Answer 2

First, personsArray variable is not a outlet. So, remove outlet property and replace weak with strong:
#property (strong,nonatomic) NSMutableArray *personsArray;
Second, need to initialize NSMutableArray before using it, maybe in viewDidLoad:
- (void)viewDidLoad
{
[super viewDidLoad];
_personsArray = [NSMutableArray new];
}