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up vote 0 down vote favorite

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

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2 Answers 2

up vote 0 down vote accepted

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);
share|improve this answer
    
I understand your solution. So you we are just creating a mutable array of many Person objects? How do I reach the content of the different Persons? I already printed the objects into NSLog: here is the code in fiddle: jsfiddle.net/reneil/7pEbr –  r3n Jun 3 at 8:16
    
You can view my edit :) –  hoptqVN.dev Jun 3 at 8:58
    
I changed Person.h, Person.m and ViewController.m. –  hoptqVN.dev Jun 3 at 9:01
    
works great thank you! –  r3n Jun 3 at 11:59
    
I'm trying to sum up the values of all amounts, but cannot find the right syntax for it: jsfiddle.net/reneil/ZqUF4 :/ –  r3n Jun 3 at 13:27
up vote 0 down vote

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];
}
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