On Aug 9, 2009, at 9:59 PM, Adam Gerson wrote:
I would like to insert objects out of order into an NSMutableArray.
I create the array with
NSMutableArray* cards = [[NSMutableArray alloc] initWithCapacity:5];
When I try to call
[cards insertObject:card atIndex:4];
I get the error:
*** -[NSCFArray insertObject:atIndex:]: index (4) beyond bounds (1)
Why doesn't this work?
Thanks,
Adam
Hi, Adam,
-insertObject:atIndex: requires the index to be within the existing
bounds of the array. -initWithCapacity: doesn't fill the array--it
only gives your array an internal "hint" as to what its size may be;
it isn't filling it, as you may know, with anything. On modern
systems, my understanding is that the benefits of using -
initWithCapacity: over -init are generally negligible.
To reframe this: If you were to be inserting an object (card) at index
4 of your array (cards) after -initWithCapacity:, what would happen if
you were to access the object at index 1, 2, or 3?
You'll need to insert objects sequentially and "build up" to the
proper array size with the "card" object at the right position.
The documentation on the methods you referenced will likely be helpful
on all these points.
Cheers,
Andrew
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