複数画面A、Bから呼ばれる画面Cを閉じた時にunwindを使って遷移元に戻す方法

やりたいこと

複数画面A、Bから呼ばれる画面Cを閉じた時にunwindを使って遷移元に戻す。
遷移元の「@IBAction func unwind(segue: UIStoryboardSegue)」で処理を行いたいので「dismissViewControllerAnimated」は使いたくない。

画面

左上：画面A 右上：画面B 下：画面C

やり方

単純に「@IBAction func unwind：」の名前を同じにするだけでできた。
ここまで辿り着くのに凄い時間かかったよorz

画面A

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func unwind(segue: UIStoryboardSegue)
    {
    }

    @IBAction func click(sender: UIButton)
    {
        self.performSegueWithIdentifier("toC", sender: nil)
    }

    @IBAction func click2(sender: UIButton)
    {
        self.performSegueWithIdentifier("toB", sender: nil)
    }
}

画面B

class View2Controller: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func unwind(segue: UIStoryboardSegue)
    {
    }

    @IBAction func click(sender: UIButton)
    {
        self.performSegueWithIdentifier("toC", sender: nil)
    }
}

画面C

class View3Controller: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}