Re: NSMutableArray & Pointers
Re: NSMutableArray & Pointers
- Subject: Re: NSMutableArray & Pointers
- From: Michael Becker <email@hidden>
- Date: Fri, 22 Oct 2004 01:48:31 +0200
Am 21.10.2004 um 14:58 schrieb stephane sudre:
What is happening to the pointer-Variable?? As soon as I try to
invoke [ pointer size] in the last line of my code, the app crashes.
Is there any way to be able to reasonably perform an "if
(pointer==nil)" statement?
AFAIK, it mostly depends on whether [ objectAtIndex:] is returning the
object directly or a [[retain] autorelease] pointer. Probably the
first one. Anyway, it's up to you to manage retaining/releasing. If
you really want to keep track of pointer, you need to retain it before
calling removeObjectAtIndex:.
Actually, my general idea was to create a cascading-delete-mechanism.
Think of a picture library and a shopping cart. If I move an image to
the shopping cart, there will be a "pointer"-Variable in the cart that
points to the original image. If I remove the original image from the
library (the NSMutableArray), I want the shopping cart to remove that
image, too.
So I really do not even want to retain the image, I merely want to
check if "pointer" is still pointing to an existing NSImage object.
However, I solved the problem in a (conceptually) different way.
Finally, why pointer should be(come) nil when it's deallocated?
Hm, I think I just assumed it would. I thought a pointer that does not
point to any object is a nil-Pointer. However, it seems as though it
just keeps on pointing to the same address, giving to you whatever
there is...
Anyway, thanks for you replies! Makes me realize that I should take a
deeper look at memory management stuff :-)
Kind regards,
Michael
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