Nothing prevents using a stale cache pointer. The stale cache still contains correct data, so using it is benign, up until it gets deallocated. A stale cache p

Nothing prevents using a stale cache pointer. The stale cache still contains correct data, so using it is benign, up until it gets deallocated. A stale cache pointer may become wrong if a method implementation is replaced, e.g. by a category, but replacing a method while calling it in another thread is inherently racey.