侧滑动手势无法正常工作

Question

我有一个整数类型的变量，当我想向左滑动时我想将变量增加一。相反，用一个向右滑动的姿势将一个变量减去一个。

问题是当我向左滑动时，switch语句不识别并执行代码，例如当变量为1时。它只在我回过头来执行它。为什么switch语句也不识别向左滑动语句。我目前只是输出到控制台。

class ViewController: UIViewController {

//counter varaible
var counter:Int = 0


override func viewDidLoad() {
    super.viewDidLoad()

    println(counter)

    //swipe left
    let swipeLeft:UISwipeGestureRecognizer = UISwipeGestureRecognizer(target: self, action: "swipedLeft:")
    swipeLeft.direction = UISwipeGestureRecognizerDirection.Left
    view.addGestureRecognizer(swipeLeft)

    //swipe right

    let swipeRight:UISwipeGestureRecognizer = UISwipeGestureRecognizer(target: self, action: "swipedRight:")
    swipeRight.direction = UISwipeGestureRecognizerDirection.Right
    view.addGestureRecognizer(swipeRight)
}

//swiped Left
func swipedLeft(didLeft:UISwipeGestureRecognizer) {

    counter += 1
    println(counter)
}


//swiped right
func swipedRight(didRight:UISwipeGestureRecognizer) {

    counter -= 1
    println(counter)

    switch counter {
    case 1:
        println("one")
    case 2:
        println("two")
    default:
        println("bye")
    }


}