排序图像数组

Question

我正在使用swift编写游戏，我想创建一个代码，让我可以在每x秒内对一组图像进行排序。这是5张图像，其思路是每2秒钟，图像的位置会发生变化而无法重复拍摄图像。

所以会有很多组合：

1,2,3,4,5

5,4,3,2,1

1,3,2,5,4

等...

以上是我制作的代码，但我认为这不是最好的方法。

var timer：NSTimer！

func startTimer() {
    if timer != nil {
        timer.invalidate()
    }

    timer = NSTimer.scheduledTimerWithTimeInterval(0.5, target: self, selector: "sortImg", userInfo: nil, repeats: true)
}

// imagens de elementos de alimentação
@IBOutlet weak var imgCoracao: UIImageView!
@IBOutlet weak var imgCoxinha: UIImageView!
@IBOutlet weak var imgSerie: UIImageView!
@IBOutlet weak var imgSushi: UIImageView!
@IBOutlet weak var imgTod: UIImageView!

func sortImg() {
    let rand = arc4random_uniform(4)

    if rand == 0 {
        imgCoracao.image = UIImage(named: "icon_coxinha.png")
        imgCoxinha.image = UIImage(named: "icon_toddy.png")
        imgSerie.image = UIImage(named: "icon_sushi.png")
        imgSushi.image = UIImage(named: "icon_serie.png")
        imgTod.image = UIImage(named: "icon_coracao.png")

    } else if rand == 1 {
        imgCoracao.image = UIImage(named: "icon_coxinha.png")
        imgCoxinha.image = UIImage(named: "icon_sushi.png")
        imgSerie.image = UIImage(named: "icon_toddy.png")
        imgSushi.image = UIImage(named: "icon_coracao.png")
        imgTod.image = UIImage(named: "icon_serie.png")
    } else if rand == 2 {
        imgCoracao.image = UIImage(named: "icon_serie.png")
        imgCoxinha.image = UIImage(named: "icon_coracao.png")
        imgSerie.image = UIImage(named: "icon_sushi.png")
        imgSushi.image = UIImage(named: "icon_toddy.png")
        imgTod.image = UIImage(named: "icon_coxinha.png")
    }


}

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

最好的方法是什么？我尝试使用arc4random_uniform和If Else语句实现一个函数，但我无法手动覆盖所有可能性。我不知道如何实现时间因素来触发变化。