NSMutableArray not accessible throughout my class?

Question

I'm really frustrated after spending like three hours googling around to solve this problem!! It's probably an easy solution to it aswell.

I'm creating a really simple TableView app for the iPhone. It's supposed to fetch an XML-document and parse it (already fixed) and then put the data into objects called HPobject! One HPobject represents one day of data from the XML-file. Anyhow!

Then I want the object to be stored in a NSMutableArray so I can grab it later when I'm creating the table rows. But I can't access it! My NSMutableArray is ALWAYS null! No matter what I do!

Here's my code:

//THE .h FILE
#import "TBXML.h"
#import "HPobject.h"

@interface RootViewController : UITableViewController {
    NSMutableArray *listOfItems;
}

- (void)traverseElement:(TBXMLElement *)element;

//THE .m FILE
#import "RootViewController.h"
#import "HPobject.h"

@implementation RootViewController

- (void)viewDidLoad
{   
    NSMutableArray *listOfItems = [[NSMutableArray alloc] init];
    TBXML * tbxml = [[TBXML tbxmlWithURL:[NSURL URLWithString:@"http://www.hpprov.se/istasts.php?q=xxxxxxx"]] retain];

    if (tbxml.rootXMLElement)
        [self traverseElement:tbxml.rootXMLElement]; //Works fine!

    [tbxml release];
    [super viewDidLoad];
}

- (void) traverseElement:(TBXMLElement *)element {    
    do {
//Lots of parsing code which all works fine and gets me the variables up next!

            HPobject *currentObject = [[HPobject alloc] init];
            currentObject.antalRegistrerade = numRegistrerade;
            currentObject.inkomstBrutto = numBrutto;
            currentObject.inkomstNetto = numNetto;

            [listOfItems addObject:currentObject];

            NSLog(@"Array: %@", listOfItems); //RETURNS null!
            NSLog(@"Reg: %@, Net: %@, Brutt: %@", currentObject.antalRegistrerade, currentObject.inkomstNetto, currentObject.inkomstBrutto); //Returns the correct values!

            NSLog(@"%d stycken!", listOfItems.count); //Returns 0!! :(
            [currentObject release];

    } while ((element = element->nextSibling));  
}

Why does is return NULL?!?? :( And why is the count 0??

Hjalmar
– Hjalmar

2011-04-14 10:12:07 +00:00
Commented Apr 14, 2011 at 10:12 — Hjalmar
– Hjalmar, Commented Apr 14, 2011 at 10:12

Till · Accepted Answer · 2011-04-14 10:13:48Z

3

You are defining listOfItems locally in viewDidLoad and then you try to access that in another method.

Make sure you are using an instance variable defined in your interface definition (header).

replace this line in viewDidLoad:

NSMutableArray *listOfItems = [[NSMutableArray alloc] init];

with

listOfItems = [[NSMutableArray alloc] init];

answered Apr 14, 2011 at 10:13

Till

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3 Comments

Hjalmar Over a year ago

Thanks for the quick reply! And... how do I do that? I know I should read a book on Objective-C and its fantastic implementation, and I will, but for now I need a quick answer! Thank you!

Rengers Over a year ago

Even better would be to use a (synthesized) getter/setter: self.listOfItems = [NSMutableArray array];

Till Over a year ago

See my solution - simply remove "NSMutableArray *" from viewDidLoad.

Max · Accepted Answer · 2011-04-14 10:15:24Z

2

I suppose that listOfItems is an ivar. So to fix your problem change this:

NSMutableArray *listOfItems = [[NSMutableArray alloc] init];

to this

listOfItems = [[NSMutableArray alloc] init];

answered Apr 14, 2011 at 10:15

Max

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1 Comment

gnasher729 Over a year ago

As a rule, you should use instance variables starting with an underscore character. That makes it much more obvious that you are assigning to an instance variable.

Jorge · Accepted Answer · 2011-04-14 10:15:25Z

1

Take a look at the scope of your array. You have created that as a variable of another method. It will not visible in others. Make an instance var.

answered Apr 14, 2011 at 10:15

Jorge

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