ios – 集合视图单元格不显示

我想显示尽可能多的collectionViewCells与按钮,因为我的数组中有字符串.但是当我启动模拟器时,只有CollectionView的背景,没有显示单元格.什么可能是错误？

以下是我在CollectionViewController中附加到main.storyboard中的CollectionView的代码：

class CollectionViewController: UICollectionViewController {

var Array = [String]()

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

    Array = ["1","2","3","4","5"]
}

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

func collectionView(collectionView: UICollectionView,numberOfItemsSection section: Int) -> Int {
    return Array.count
}

override func
    collectionView(collectionView: UICollectionView,cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {

        var cell = collectionView.dequeueReusableCellWithReuseIdentifier("cell",forIndexPath: indexPath) as! UICollectionViewCell

        var button = cell.viewWithTag(1) as! UIButton
        button.titleLabel?.text = Array[indexPath.row]

        return cell
}

}

这些是Collection View Controller的连接：

故事板上的视图控制器：