您如何扩展现代收藏查看单元格默认内容配置？

Question

苹果的使用默认的单元格内容配置以设置两行文本，

    func cellRegistrationHandler(cell: UICollectionViewListCell, indexPath: IndexPath, id: String) {
        let reminder = Reminder.sampleData[indexPath.item]
        var contentConfiguration = cell.defaultContentConfiguration()
        contentConfiguration.text = reminder.title
        contentConfiguration.secondaryText = reminder.dueDate.dayAndTimeText
        contentConfiguration.secondaryTextProperties.font = UIFont.preferredFont(forTextStyle: .caption1)
        cell.contentConfiguration = contentConfiguration
    }

我将如何开始将其扩展到包含第三行文本？我想保留内置的文本，secondaryText和配件控制（该教程在每个单元格上具有完成按钮），同时还添加了自定义UI元素。我认为这是可能的，因为Apple使用术语“构图集合视图”，但我不确定如何完成此操作。是否有可能，还是需要注册自定义uicollectionViewCell子类？

Answer 1

我认为您必须使用自定义uicontentView和uicontentConfiguration对象来完成您在说的内容。

话虽如此，这是内容config/view/collection -list的简化示例 -

// MARK: UIContentConfiguration

struct MyCellContentConfiguration: UIContentConfiguration {
    var text: String?
    
    func makeContentView() -> UIView & UIContentView {
        MyCellContent(configuration: self)
    }
    
    func updated(
        for state: UIConfigurationState
    ) -> MyCellContentConfiguration {
        self
    }
}

// MARK: UIContentView

class MyCellContent: UIView, UIContentView {
    var configuration: UIContentConfiguration {
        get { cellConfiguration }
        set { configureCell() }
    }
    private var cellConfiguration: MyCellContentConfiguration
    private weak var label: UILabel!
    
    init(configuration: MyCellContentConfiguration) {
        self.cellConfiguration = configuration
        super.init(frame: .zero)
        addLabel()
        configureCell()
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    private func addLabel() {
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        addSubview(label)
        NSLayoutConstraint.activate([
            label.topAnchor.constraint(equalTo: layoutMarginsGuide.topAnchor),
            label.bottomAnchor.constraint(equalTo: layoutMarginsGuide.bottomAnchor),
            label.leadingAnchor.constraint(equalTo: layoutMarginsGuide.leadingAnchor),
            label.trailingAnchor.constraint(equalTo: layoutMarginsGuide.trailingAnchor),
        ])
        self.label = label
    }
    
    private func configureCell() {
        label.text = cellConfiguration.text
    }
}

// MARK: UICollectionViewController

class MyCollectionViewController: UICollectionViewController {
    typealias DataSource = UICollectionViewDiffableDataSource<Int, String>
    typealias Snapshot = NSDiffableDataSourceSnapshot<Int, String>
    
    private var dataSource: DataSource!
    
    init() {
        let configuration =
        UICollectionLayoutListConfiguration(appearance: .grouped)
        let layout = UICollectionViewCompositionalLayout
            .list(using: configuration)
        super.init(collectionViewLayout: layout)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // register cells
        let cellRegistration =
        UICollectionView.CellRegistration<
            UICollectionViewListCell, String
        > { cell, indexPath, text in
            var contentConfiguration = MyCellContentConfiguration()
            contentConfiguration.text = text
            cell.contentConfiguration = contentConfiguration
        }
        // configure datasource
        dataSource = DataSource(collectionView: collectionView) {
            collectionView, indexPath, itemIdentifier in
            collectionView.dequeueConfiguredReusableCell(
                using: cellRegistration,
                for: indexPath,
                item: itemIdentifier) }
        // configure snapshot
        var snapshot = Snapshot()
        let items = ["Ayo", "what da dog doin?"]
        let sections = [items]
        let sectionKeys = [Int](0..<sections.count)
        snapshot.appendSections(sectionKeys)
        sectionKeys.forEach {
            snapshot.appendItems(
                sections[$0],
                toSection: $0) }
        // inject snapshot & datasource
        dataSource.apply(snapshot)
        collectionView.dataSource = dataSource
    }
}