我的代码如下：

super.viewDidLoad()
    // Register cell classes
    self.collectionView!.registerClass(UICollectionViewCell.self,forCellWithReuseIdentifier: reuseIdentifier)
}


    override func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
    //#warning Incomplete method implementation -- Return the number of sections
    return 4
}


override func collectionView(collectionView: UICollectionView,numberOfItemsInSection section: Int) -> Int {
    //#warning Incomplete method implementation -- Return the number of items in the section
    return 10
}

override func collectionView(collectionView: UICollectionView,cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier,forIndexPath: indexPath) as! UICollectionViewCell

    // Configure the cell

    return cell
}

我有单元格的重用标识符,因为它在文件中命名.

在运行中,我可以看到CollectionView的背景,但不是我应该看到的40个单元格.怎么了？