Set pointers to nil after release?

Question

After releasing objects is it best to set the pointers to nil? Thats what I have been doing, just wanted to ask if its necessary, good practice or overkill?

Answer 1

At times this can be crucial, as I just found out. I use a camera in my game which keeps a pointer to a generic target. If you return to the main menu from a level then it clears the level from memory but keeps the camera and game layers.

-(void) dealloc {
    [target release];
    target = nil;
    [super dealloc];
}

Since the camera will exist longer than the target, it's best to set target to nil, otherwise when the level loads again and you set a new target:

-(void) setTarget:(CCNode *)aTarget {
    [target release];
    target = [aTarget retain];
    [self update:0];
}

It will crash on that release if the target is junk and not nil. Sending a message to nil is fine, but not to some arbitrary junk memory. That gives me a EXC_BAD_ACCESS.