Object remains null after set

Question

I'm trying to set the properties of an object, but it remains null. Can anyone tell me why, please?

Declaration:

@property (nonatomic, strong) ListItem *listItem

Here's the code:

NSLog(@"Selected: %@", [self.fetchedResultsController objectAtIndexPath:indexPath]);
[listItem setCategory:[self.fetchedResultsController objectAtIndexPath:indexPath]];
NSLog(@"set %@", listItem);

and the output:

2012-06-28 14:47:43.037 MarketList[10508:fb03] Selected: <Category: 0xb72a9e0> (entity: Category; id: 0xb7252e0 <x-coredata://F9BFC1DF-1D80-477E-9BC6-3C0949AD922F/Category/p2> ; data: {
listItem = "<relationship fault: 0x6d29930 'listItem'>";
name = "Teste 2";})
2012-06-28 14:47:43.038 MarketList[10508:fb03] set (null)

possible duplicate of [Cannot add items to an NSMutableArray ivar](http://stackoverflow.com/questions/7125326/cannot-add-items-to-an-nsmutablearray-ivar) and http://stackoverflow.com/questions/3683761/nsmutablearray-addobject-not-affecting-count http://stackoverflow.com/questions/1827058/nsmutablearray-addobject-not-working — jscs, Jun 28 '12 at 19:00

score 1 · Answer 1 · answered Jun 28 '12 at 18:28

there is a semicolon missing in your property declaration (assuming this is just a typo though).
Do you ever actually initialize the ListItem? (ie listItem = [[ListItem alloc] init]; If you don't, the pointer to it will be nil, and would cause exactly this behavior (calls with a nil pointer are just ignored).

score 1 · Accepted Answer · answered Jun 28 '12 at 18:38

1

Your variable listItem holds nil, not an instance of ListItem. You never actually point it to an instance of ListItem, so it's still nil at the end of your method. Sending a message to nil does not cause an object to magically spring into existence to receive the message — nil just silently swallows it. You have to create your ListItem first and then set its property.

answered Jun 28 '12 at 18:38

Chuck

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Of course --' I changed the variable that was using and forgot to create it, thanks! – Junior Jun 28 '12 at 18:44

score 0 · Answer 3 · answered Jun 28 '12 at 18:42

NSLog(@"Selected: %@", [self.fetchedResultsController objectAtIndexPath:indexPath]);
listItem = [self.fetchedResultsController objectAtIndexPath:indexPath];
[listItem setCategory:[self.fetchedResultsController objectAtIndexPath:indexPath]];
NSLog(@"set %@", listItem);

itsji10dra · Answer 4 · 2013-12-27T12:23:06.680

0

Just alloc the object before using it. Alloc it in viewDidLoad.

edited Dec 27 '13 at 12:23

answered Dec 26 '13 at 13:17

itsji10dra

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Object remains null after set

4 Answers4