Why is my NSMutableArray returning nill?

I have a very simple task: add the contents of a textField to an NSMutableArray.The Problem is the array is returning nill. I believe that it has something to do with the f开发者_如何学Cact that the array I'm using is declared as an instance variable.

/*
 IBOutlet NSTextField *textField;
 IBOutlet NSTabView *tableView;
 IBOutlet NSButton *button;
 NSMutableArray *myArray;
 */

#import "AppController.h"


@implementation AppController


-(IBAction)addNewItem:(id)sender
{
    NSString *string = [textField stringValue];
    NSLog(@"%@",string);

    [myArray addObject:string];
    NSLog(@"%d",[myArray count]);//this outputs 0 why is that?

}

Did you do the following somewhere?

myArray = [[NSMutableArray alloc] init];

If you don't do something like that, myArray is just a null pointer and the addObject call will just silently do nothing.

Edit: The idea here is that no NSMutableArray object has been created if you just have a pointer variable. Until the alloc and init are called, there's no object.

Check out this CocoaDev page for more information on NSMutableArray and its use. And the Apple documentation has information on the NSMutableArray methods.

Also, this is essentially the same question as this SO question.