为什么不去CollectionViewCell？

问题描述

我注意到调试时Topics CollectionViewCell没有消失。为什么会这样？ 所有单元格都正确，但是collectionview不可用。

该项目的链接在下面。您也可以从那里看。

这里我定义单元格。

  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
    }
}

在这里我定义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)
    }
    
}

**此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,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)
    }
}

@L_502_0@

解决方法

在执行期间，这些行无用，因为collectionView?为零

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

您需要通过首先初始化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