Question

I have found that [object_name retain] increases that object reference count by 1 and [object_name release] decreases that object reference count by 1. [pool drain] applies release on all the objects it refers to.

Now I’m confused. What happens to an object when there is no reference to it?
release and drain just decrementing reference count so does memory is actually released on zero reference count or do I still have an object with a zero reference count?

I also found if here

[pool drain] // makes my Object str3 reference count Zero

NSLog(@"%li",[str3 length]); // it works, object may be not destroyed yet!

// other code here

But

[pool drain]

// other code here

NSLog(@"%li",[str3 length]); // not working, may be it is destroyed now!

Answer 1

I think the object will be destroyed after a zero retain count, and cannot be used anymore. Please refer here for more.