Array count is 0 directly after calling addObject

Question

Why is the count of otherArray 0 even though self.array has N items and the for loop is executing N times?

for (MyObject *obj in self.array) 
{
    [self.otherArray addObject:obj];
    NSLog(@"Num items: %d", [self.otherArray count]);
}

self.otherArray is an NSMutableArray*

LATER: Doh!, forgot to call alloc/init (I come from a language where the equivalent of addObejct will create the array if necessary).

possible duplicate of [NSMutableArray addObject not affecting count?](http://stackoverflow.com/questions/3683761/nsmutablearray-addobject-not-affecting-count) and [NSMutableArray addObject: not working](http://stackoverflow.com/questions/1827058/nsmutablearray-addobject-not-working) — jscs, Jan 12 '12 at 18:47

score 2 · Answer 1 · answered Jan 12 '12 at 18:44

2

Best guess: You have not initialized self.otherArray correctly.

Second best guess: self.otherArray is not mutable.

Test this by posting your initialization code.

answered Jan 12 '12 at 18:44

PengOne

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Doh, didn't call alloc/init (I've come from a language where the equivalent of calling addObject will also create the array if necessary.) – Gruntcakes Jan 12 '12 at 18:47
@Mungbeans You are not alone in this mistake. Let me know if that doesn't fix the issue. – PengOne Jan 12 '12 at 18:47

score 0 · Accepted Answer · answered Jan 12 '12 at 18:46

In this case, the most common reason this would occur is if self.otherArray isn't initialized. If you add a check to self.otherArray, I would suspect it is nil. If you added:

self.otherArray = [[NSMutableArray alloc] init];

right before the other code, I suspect it would work as intended.

Array count is 0 directly after calling addObject

2 Answers2