Question

我在另一个uicollectionview中有一个uicollectionview。当我水平滚动单元格时，如您所见，“顶部单元格”（包含其他集合视图的单元格）未出列：

如您所见，“Randonnées”与“Aborigènes”相同。

我已尽力尝试prepareForReuse（），但它似乎无法正常工作。我知道其他人遇到了一个非常相似的问题，但没有一个相关的主题对我有用：/

以下是我的一些代码：

class X3ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {

// MARK: Variables
let cellID = "pouet"
let delegate = UIApplication.shared.delegate as! AppDelegate
var cell : X3ContentCollectionViewCell?

// MARK: UI
let titleView : UIView = {
    let view = UIView()
    view.translatesAutoresizingMaskIntoConstraints = false
    return view
}()

 var mainCollectionView : UICollectionView = {
    let layout = UICollectionViewFlowLayout()
    let view = UICollectionView(frame: .zero, collectionViewLayout: layout)
    view.collectionViewLayout = layout
    layout.scrollDirection = .horizontal
    layout.minimumLineSpacing = 0
    view.isPagingEnabled = true
    view.translatesAutoresizingMaskIntoConstraints = false
    view.backgroundColor = .white
    return view
}()

var menuBar: X3MenuBar?

override func viewWillAppear(_ animated: Bool) {
    print(delegate.ds.X3data)
}

// MARK: ViewDidLoad
override func viewDidLoad() {
    super.viewDidLoad()
    view.backgroundColor = UIColor.blue
    mainCollectionView.dataSource = self
    mainCollectionView.delegate = self
    mainCollectionView.register(X3ContentCollectionViewCell.self, forCellWithReuseIdentifier: cellID)
    menuBar = X3MenuBar()
    menuBar?.view.translatesAutoresizingMaskIntoConstraints = false
    menuBar?.rootController = self
    addMenuScrollView()
    addMainView()

}

// MARK: Methods
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return delegate.ds.X3data!.count
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    cell = mainCollectionView.dequeueReusableCell(withReuseIdentifier: cellID, for: indexPath) as? X3ContentCollectionViewCell
    cell?.indexOfContent = indexPath.row
    return cell!
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    return CGSize(width: view.frame.width, height: view.frame.height-25)
}

func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
    let screenWidth = UIScreen.main.bounds.size.width
    let itemIndex = Int(targetContentOffset.pointee.x / screenWidth)
    menuBar?.scrollToItemIndex(item: itemIndex)

}

func scrollToItemIndex(item: Int)  {
    mainCollectionView.selectItem(at: IndexPath(row: item, section: 0), animated: true, scrollPosition: .centeredHorizontally)
delegate.ds.X3index = item
}



//MARK: UI Methods


func addMainView() {
    view.addSubview(mainCollectionView)
    mainCollectionView.topAnchor.constraint(equalTo: (menuBar?.view.bottomAnchor)!).isActive = true
    mainCollectionView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
    mainCollectionView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
    mainCollectionView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
}

func addTitleView() {
    view.addSubview(titleView)
    titleView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
    titleView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
    titleView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
    titleView.heightAnchor.constraint(equalToConstant: delegate.gfx.X1ViewTitleHeigth!).isActive = true
}

func addMenuScrollView() {
    view.addSubview((menuBar?.view)!)
    menuBar?.view.topAnchor.constraint(equalTo: topLayoutGuide.bottomAnchor).isActive = true
    menuBar?.view.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
    menuBar?.view.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
    menuBar?.view.heightAnchor.constraint(equalToConstant: 30).isActive = true

}

deinit {
    delegate.ds.X3data = nil
}

}

另一个重要部分：

class X3ContentCollectionViewCell: UICollectionViewCell, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {

let cellId = "pouet"
let delegate = UIApplication.shared.delegate as! AppDelegate
var indexOfContent = 0

 var customCollectionView : UICollectionView = {
    let layout = UICollectionViewFlowLayout()
    layout.scrollDirection = .vertical
    layout.minimumLineSpacing = 0
    layout.minimumInteritemSpacing = 0
    let cv  = UICollectionView(frame: .zero, collectionViewLayout: layout)
    cv.collectionViewLayout = layout

    cv.backgroundColor = .white
    cv.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: 20, right: 0)
    cv.translatesAutoresizingMaskIntoConstraints = false
    return cv

}()

override init(frame: CGRect) {
    super.init(frame: frame)
    customCollectionView.register(X3ContentMenuCellCollectionViewCell.self, forCellWithReuseIdentifier: cellId)
    customCollectionView.dataSource = self
    customCollectionView.delegate = self
    addSubview(customCollectionView)
    customCollectionView.topAnchor.constraint(equalTo: topAnchor).isActive = true
    customCollectionView.leftAnchor.constraint(equalTo: leftAnchor).isActive = true
    customCollectionView.rightAnchor.constraint(equalTo: rightAnchor).isActive = true
    customCollectionView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -5).isActive = true
    customCollectionView.reloadData()
}

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

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return ((delegate.ds.X3data?[self.indexOfContent] as! NSDictionary)["images"] as! NSArray).count
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    if indexPath.item == 0 {
    return CGSize(width: frame.size.width, height: 170)
    } else if indexPath.item == 3 {
        return CGSize(width: frame.size.width, height: 170)
    }else {
        return CGSize(width: frame.size.width/2, height: 120)
    }
}

override func prepareForReuse() {

}

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = customCollectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! X3ContentMenuCellCollectionViewCell
    print((((delegate.ds.X3data?[self.indexOfContent] as! NSDictionary)["images"] as! NSArray)[indexPath.row] as! NSDictionary)["image"])
    cell.X3Label.text = "\((((delegate.ds.X3data![self.indexOfContent] as! NSDictionary)["images"] as! NSArray)[indexPath.row] as! NSDictionary)["image"]!) \(self.indexOfContent)"
    cell.X3ImageView.image = UIImage(named: (((delegate.ds.X3data?[self.indexOfContent] as! NSDictionary)["images"] as! NSArray)[indexPath.row] as! NSDictionary)["image"] as! String)
    cell.X3ImageView.contentMode = .scaleAspectFill
    cell.X3ImageView.clipsToBounds = true

    if indexPath.item == 0 {
        cell.X3Label.font = delegate.gfx.font(style: 2)
    } else if indexPath.item == 3 {
        cell.X3Label.font = delegate.gfx.font(style: 2)
    }else {
        cell.X3Label.font = delegate.gfx.font(style: 4)
    }
    return cell
}



deinit {
}
}

Answer 1

mrabins是对的。试试这个，看它是否有效。似乎在设置indexOfContent时，您的数据已准备就绪。所以只需重新加载它。

var indexOfContent = 0 {
   didSet {
       customCollectionView.reloadData()
    }
}

Answer 2

如果我正确理解你。当您需要重新加载内容时，您无法调用reloadData（）。

另外，如果你要覆盖prepareForReuse（），为什么还有一个空的实现

dequeueReusableCell不会在3个单元格后出列

2 个答案: