为啥不去 CollectionViewCell？

Posted 2023-03-14

【中文标题】为啥不去 CollectionViewCell？

【英文标题】：Why doesn't go CollectionViewCell?为什么不去 CollectionViewCell？

【发布时间】：2020-10-18 13:29:34

【问题描述】：

我注意到我调试时 Topics CollectionViewCell 并没有消失。为什么会这样？ 所有单元格都正确，但集合视图不可用。

项目的链接如下。你也可以从那里看。

我在这里定义单元格。

  extension ArticlesVC: UITableViewDelegate, UITableViewDataSource 
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int 
        return models.count
    
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell 
        let cell = tableView.dequeueReusableCell(withIdentifier: CollectionTableViewCell.identifier, for: indexPath) as! CollectionTableViewCell
        cell.configure(with: models)
        return cell
    
    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat 
        return 200
    


struct Model 
    let text: String
    let imageName: String
    
    init(text: String, imageName: String) 
        self.text = text
        self.imageName = imageName
    

我在这里定义 CollectionTableViewCell

 class CollectionTableViewCell: UITableViewCell 
    
    static let identifier = "CollectionTableViewCell"
    
    var collectionView: UICollectionView?
    
    var models = [Model]()
    
    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) 
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        
        collectionView?.register(TopicsCollectionViewCell.self, forCellWithReuseIdentifier: TopicsCollectionViewCell.identifier)
        
        collectionView?.delegate = self
        collectionView?.dataSource = self
        
        let layout = UICollectionViewFlowLayout()
        layout.scrollDirection = .horizontal
        collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
        contentView.addSubview(collectionView!)
    
    
    required init?(coder: NSCoder) 
        fatalError("init(coder:) has not been implemented")
    
    override func layoutSubviews() 
        super.layoutSubviews()
        collectionView?.frame = contentView.bounds
    
    func configure(with models: [Model]) 
        self.models = models
        collectionView?.reloadData()
        
    
    

extension CollectionTableViewCell: UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout 
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int 
        return models.count
    
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell 
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: TopicsCollectionViewCell.identifier, for: indexPath) as! TopicsCollectionViewCell
        cell.configure(with: models[indexPath.row])
        return cell
    
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize 
        return CGSize(width: 250, height: 250)
    
    

**This TopicsCollectionViewCell **

    class TopicsCollectionViewCell: UICollectionViewCell 
    
    static let identifier = "TopicsCollectionViewCell"
    
    let titleLabel: UILabel = 
        let label = UILabel()
        label.text = "label"
        return label
    ()
    
    let photoImage: UIImageView = 
       let imageView = UIImageView()
        return imageView
    ()
    
    override init(frame: CGRect) 
        super.init(frame: frame)
        contentView.addSubview(titleLabel)
        contentView.addSubview(photoImage)
    
    
    required init?(coder: NSCoder) 
        fatalError("init(coder:) has not been implemented")
    
    
    override func layoutSubviews() 
        super.layoutSubviews()
        photoImage.frame = CGRect(x: 3,
                                  y: 3,
                                  width: contentView.width - 6,
                                  height: 150)
        titleLabel.frame = CGRect(x: 3,
                                  y: photoImage.bottom + 5,
                                  width: contentView.width - 6,
                                  height: contentView.height - photoImage.height - 6)
    
    
    public func configure(with model: Model) 
        print(model)
        self.titleLabel.text = model.text
        self.photoImage.image = UIImage(named: model.imageName)
    

This link is project with github

【参考方案1】：

在执行期间，这些行是无用的，因为collectionView? 是 nil

collectionView?.register(TopicsCollectionViewCell.self, forCellWithReuseIdentifier: TopicsCollectionViewCell.identifier) 
collectionView?.delegate = self
collectionView?.dataSource = self

你需要先初始化collectionView来重新排序代码

let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
contentView.addSubview(collectionView!)
collectionView?.register(TopicsCollectionViewCell.self, forCellWithReuseIdentifier: TopicsCollectionViewCell.identifier) 
collectionView?.delegate = self
collectionView?.dataSource = self