如何在collectionView中插入项目？Swift3

// 数据源数组
var items = ["Item 1", "Item 2", "Item 3"]

// 实现数据源方法
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return items.count
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath)
    cell.textLabel.text = items[indexPath.item]
    return cell
}

// 插入新项目
let newItem = "New Item"
items.insert(newItem, at: 0)

// 更新collectionView
let indexPath = IndexPath(item: 0, section: 0)
collectionView.insertItems(at: [indexPath])