计数器没有正确生成

Question

基本上我想要做的是编写一个计数器，每当两个对象（Wall和amp; Player）发生碰撞时加一个计数器。这是我的全部代码：

var PlayerTimer : NSTimer!
@IBOutlet var Wall: UIImageView!
@IBOutlet var Player: UIImageView!
@IBOutlet  var CountLabel: UILabel!
var CountNumber : Int!

func Add() {

    CountNumber = CountNumber + 1
    CountLabel.text = "\(CountNumber)"
}

func PlayerMoving() {

    Player.center = CGPointMake(Player.center.x, Player.center.y + 1)
    if (CGRectIntersectsRect(Player.frame, Wall.frame)){
        Add()
    }
}
override func viewDidLoad() {
    super.viewDidLoad()

    CountNumber = 0
    PlayerTimer = NSTimer.scheduledTimerWithTimeInterval(0.01, target: self, selector: Selector("PlayerMoving"), userInfo: nil, repeats: true)

    // Do any additional setup after loading the view, typically from a override nib.
}
override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

但接下来发生的事情是，在玩家移动并撞到墙壁后，会添加1，但视图会重置。例如，当玩家击中墙壁并添加1时，玩家返回到视图顶部的初始位置。我想要发生的是让我的玩家在碰撞后继续朝着同一方向坠落。感谢。