Question

I was quickly going over a large project looking for memory leaks, and came across a @property (nonatomic, retain) without a corresponding release in dealloc. Oops, quick fix, I think.

After a later crash, I look closer and the setFoo method is overriden, and the value is being retained but not by the ivar – for the sake of this question, assume it’s being put into an NSDictionary.

(OK, if you don’t want to assume that – the set value is actually a CCSprite in cocos2d, setNormalSprite, and it is being added as a child, thus retained, but simply assigned to the ivar:

 - (void)setNormalSprite:(CCSprite *)sprite 
  {
    if (normalSprite) {
        [self removeChild:normalSprite cleanup:YES];
        normalSprite = nil;
    }

    normalSprite = sprite;
    [self addChild:normalSprite];

    (...omitted...)
   }

)

What is the correct keyword for a value whose setter causes the retain count to increase, but not because the ivar it’s associated with is retained?

Answer 1

retain (or strong in ARC world) is correct in your case because you’re adding your CSSprite object into another collection that retains the object.

You should set the @property to @dynamic in your @implementation too if you are not actually using an instance variable to store the object.