swift - 自定义 View 不符合协议(protocol) UICollectionViewDataSource

Question

我用 swift 3.0 编写了一个演示，并用自定义 View 包装了一个 UICollectionView。延迟加载collecionView并将当前 View 设置为数据源，但在自定义 View 扩展中遵守UICollectionViewDataSource直接报错。如何处理？

代码:

//小区ID

fileprivate let ContentCellID = "ContentCellID"

class PageContentView: UIView {

    // MARK:- lazy attributes
    fileprivate lazy var collecionView : UICollectionView = {
        // 1.create layout
        let layout = UICollectionViewFlowLayout()
        layout.itemSize = self.bounds.size
        layout.minimumLineSpacing = 0
        layout.minimumInteritemSpacing = 0
        layout.scrollDirection = .horizontal
        // 2.create UICollectionView
        let collecionView = UICollectionView(frame: CGRect.zero, collectionViewLayout: layout)
        collecionView.showsHorizontalScrollIndicator = false
        collecionView.isPagingEnabled = true
        collecionView.bounces = false
        collecionView.dataSource = self
        // register cell
        collecionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: ContentCellID)
        return collecionView
    }()
    // MARK:- define attributes
    fileprivate var childVcs : [UIViewController]
    fileprivate var parentVc : UIViewController
    // MARK:- custom constructor
    init(frame: CGRect, childVcs : [UIViewController], parentVc : UIViewController) {
        self.childVcs = childVcs
        self.parentVc = parentVc
        super.init(frame: frame)
        setupUI()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

//MARK:- 设置 UI

extension PageContentView {
    fileprivate func setupUI() {

        for childVc in childVcs {
            parentVc.addChildViewController(childVc)
        }

        addSubview(collecionView)
        collecionView.frame = bounds
    }
}

//标记:- UICollectionViewDataSource

extension PageContentView : UICollectionViewDataSource {

    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return childVcs.count
    }
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

        let cell = collecionView.dequeueReusableCell(withReuseIdentifier: ContentCellID, for: indexPath)

        let childVc = childVcs[indexPath.row]
        childVc.view.frame = cell.contentView.bounds
        cell.contentView.addSubview(childVc.view)
        return cell
    }
}

Answer 1

您忘记实现所需的方法 collectionView(_:numberOfItemsInSection:)，实现它。

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
     return childVcs.count
}

注意:方法numberOfSections(in:)如果你没有实现默认部分是 1，那么你实现的是可选方法，所以删除该方法并在 collectionView(_ :numberOfItemsInSection:) 我在上面添加的。