NSMutableArray keeps returning null

Question

I have declared a property NSMutableArray in the header file. Then I alloc, init it in the viewDidLoad method. But when I try to add an object to the array in a different method it keeps returning (null). Am I doing some obvious mistake? Please ask if you want to see some more code.

.h

@property (strong, nonatomic) NSMutableArray *myList;

.m

- (void)viewDidLoad
{
 self.dataController = [[DataController alloc]init];
 self.myList = [[NSMutableArray alloc] init];
 [super viewDidLoad];
}

[...]

NSDictionary *myObject = [self.dataController.objectList objectAtIndex:r];
[[cell textLabel]setText:[myObject objectForKey:@"title"]];
[self.myList addObject:myObject]; 
NSLog(@"myList %@",self.myList);
NSLog(@"myObject %@",myObject);

The output prints myObject but self.myList keeps returning (null). Appreciate all help!

Edit: Fixed, thank you for your answers!

• Lily Ballard: Are you sure the view has already loaded by the time you try to access the list? Maybe you should be initializing those properties in init instead.
• rdelmar: Where in the app is the code where you create myObject, add it to myList, and do the logs?
• Emil: @KevinBallard The code in the third snippet is in tableView:cellForRowAtIndexPath so I guess the problem is that this method loads before viewDidLoad. However the log in viewDidLoad returns before the log in tableView:cellForRowAtIndexPath does. I tried to move the code from viewDidLoad to (id)init but never got it to work.

Answer 1

Not sure where you are using this array. If you have to use this array before viewDidLoad is called, you can do it as,

NSDictionary *myObject = [self.dataController.objectList objectAtIndex:r];
[[cell textLabel]setText:[myObject objectForKey:@"title"]];
if (!self.myList)
 self.myList = [[NSMutableArray alloc] init];//for the first time, this will initialize
[self.myList addObject:myObject]; 

Since you are using [cell textLabel] I am assuming that you are doing this in one of the table view delegates. In that case check if you are setting self.myList = nil; any where in the class.

• Daij-Djan: it is used later than viewDidLoad -- else his code wouldnt print myObject. Or would it?
• iDev: @Daij-Djan, Cant predict that from myObject. It could be that he is setting dataController from previous class itself and initialization part for dataController is not called while executing this. But I think you are correct due to the usage of [cell textLabel] which should be done in cellForRowAtIndexpath. That should have been called after viewDidLoad. But in any case he has to add more info to his question.
• borrrden: My thoughts were that he simply initialized myObject in init as well, but didn't realize / didn't mention it.
• Emil: After a lot of debugging I finally found a little piece of code that set the list to nil. Now it works. Thanks for your help!
• iDev: @Emil, Glad to help. :) That's what I thought. :)

Answer 2

In your posted code i see no error. Set a breakpoint and look if the code where you init the array is called first.

Answer 3

I bet that viewDidLoad hasn't been called yet when the NSLogs are execute.

To ensure that the array has been initialized, try putting the initialization in your init method.

• Emil: I don't have any init method yet. When I try to add one it doesn't execute.