Is addTarget safe to use?

Question

I'm a bit skeptical recently, with the use of addTarget() to UITableViewCell in cellForRowAtIndexPath. I'm also eager to know what is the best practice to listen button event from UITableViewCell.

My confusion begins when I see I've no way to de-register the addTarget listener that I adds to an UIButton resides in UITableViewCell:

Code for cellForRowAtIndexPath:

cell.button.addTarget(self, action: "buttonClicked:", forControlEvents: UIControlEvents.TouchUpInside)

The above code registers a listener to UIButton that resides in UITableViewCell, but I see there no reference of de-registering them. I'm not sure if this process is automatic or not (to addTarget-mechanism), I haven't found any reference that said so in Apple doc (as far I've searched, at least), also.

So, my question is, is addTarget use to UITableViewCell buttons are good to use? Does they all de-registers when view controller disappears?

Or, it would be good if I use an addObserver?

override func viewDidLoad()
{
        super.viewDidLoad()
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "onCellButtonPressed:", name: "cellButtonPressed", object: nil)
}

func onCellButtonPressed(notification:NSNotification)
{
        if let sender = notification.object as? UIButton
        {
                ...
        }
}

In UITableViewCell code:

@IBAction func onButtonPressed(sender: AnyObject)
{
NSNotificationCenter.defaultCenter().postNotificationName("cellButtonPressed", object: sender)
}

Any suggestion on this, would be appreciated.

Answer 1

The target passed to addTarget is not retained. It is safe to use; you don't need to "deregister" (or remove) the target. This is the standard mechanism for control actions (like button presses) and you should use it (versus notifications).