My way of creating events is creating a cycle reference where nothings gets released

I have a bunch of objects and I try and simulate events with them.

id completedSelectorTarget;
    SEL nextTripSelector;

Then I call perform selector on the selector target.

Well I created a double reference whe开发者_如何转开发re the listener of the event completedSelectorTarget retains my object and completedSelectorTarget is retained by the object as well.

How do I avoid this? Is there a better way to do events? I thought to remove the retain on completedSelectorTarget, but then what will happen when I call perform selector? The whole thing will crash wont it? Is there a way to check if completedSelectorTarget has been released before I call perform selector? Or perhaps I'm just doing this wrong?

Yes you are correct, you should avoid circular retains.

The way to do this is to decide on an ownership model for these objects. This means deciding which object should have the final say over the life and death of these objects, and a good way to choose this is to pick the object that creates these objects as the owner and main retainer of them. It's not the only way it can be done, but that should be a good start in the right direction. All other relationships should be weak and use assign for the property. In this way you can be sure that when the owner of the objects decides that they should go away, that they will. The owner could also cause these weak links to be cleaned perhaps by calling a method that separates the weak connection by setting the target properties to nil. This is done in case any other object is hanging onto either of the objects and causing the selectors to fire on the targets that have been deallocated.

So you can remove the retain from the completedSelectorTarget properties and make weak connections between the objects.

@property (assign) __weak id completedSelectorTarget;

Once that is done, decide which object is the owner of these objects and make it retain them, either directly using @propery (retain) ..., or perhaps by storing them in a container such as an array or dictionary. When this retain, or container, is released, your object(s) should deallocate or at the very least wind up on an autorelease pool. And you now have a single owner that you can go to to make sure your objects get deallocated.

For now I'm using NSNotification Center. I notice that it crashes as well if you don't remove the observer when it is released. Still it should save me time from writing my own code.