如何将UICollectionViewDelegate的didSelectItemAt方法与Cell内开关关联

要实现开关切换时获取indexPath并联动处理逻辑，你可以给UISwitch绑定状态变化事件，通过响应链找到对应单元格并获取indexPath，最终关联到目标方法。以下是两种具体实现方式：

方式一：直接调用didSelectItemAt代理方法 #

1. 修改CustomCellView，添加开关事件监听 #

给UISwitch绑定valueChanged事件，在回调中向上遍历响应链找到所在的CustomCell，进而获取indexPath并调用代理方法：

class CustomCellView: UIView {
    private(set) var toggleSwitch = UISwitch()

    override init(frame: CGRect) {
        super.init(frame: frame)
        setupSwitch()
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
        setupSwitch()
    }

    private func setupSwitch() {
        // 将开关添加到视图并设置布局约束
        addSubview(toggleSwitch)
        toggleSwitch.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            toggleSwitch.centerXAnchor.constraint(equalTo: centerXAnchor),
            toggleSwitch.centerYAnchor.constraint(equalTo: centerYAnchor)
        ])
        
        // 绑定开关状态变化事件
        toggleSwitch.addTarget(self, action: #selector(switchToggled), for: .valueChanged)
    }

    @objc private func switchToggled() {
        // 遍历响应链找到所属的CustomCell
        var currentView: UIView? = self
        while let view = currentView {
            if let cell = view as? CustomCell {
                guard let collectionView = cell.superview as? UICollectionView,
                      let indexPath = collectionView.indexPath(for: cell),
                      let vc = collectionView.delegate as? CustomVC else { return }
                
                // 手动调用代理方法
                vc.collectionView(collectionView, didSelectItemAt: indexPath)
                break
            }
            currentView = view.superview
        }
    }
}

2. 修正CustomCell的视图设置逻辑 #

不要直接替换系统默认的contentView，而是将自定义视图添加到contentView中：

class CustomCell: UICollectionViewCell {
    override init(frame: CGRect) {
        super.init(frame: frame)
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
    }

    func setView(view: UIView) {
        // 清空原有子视图，添加新的自定义视图
        contentView.subviews.forEach { $0.removeFromSuperview() }
        view.translatesAutoresizingMaskIntoConstraints = false
        contentView.addSubview(view)
        NSLayoutConstraint.activate([
            view.topAnchor.constraint(equalTo: contentView.topAnchor),
            view.leadingAnchor.constraint(equalTo: contentView.leadingAnchor),
            view.trailingAnchor.constraint(equalTo: contentView.trailingAnchor),
            view.bottomAnchor.constraint(equalTo: contentView.bottomAnchor)
        ])
    }
}

3. 完善CustomVC的代理方法 #

修正类型转换错误（原代码中CustomView应为CustomCellView）：

class CustomVC: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
    var collectionView: UICollectionView!

    override func viewDidLoad() {
        super.viewDidLoad()
        setupCollectionView()
    }

    private func setupCollectionView() {
        let layout = UICollectionViewFlowLayout()
        layout.itemSize = CGSize(width: 200, height: 100)
        collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: layout)
        collectionView.delegate = self
        collectionView.dataSource = self
        collectionView.register(CustomCell.self, forCellWithReuseIdentifier: "CustomCell")
        view.addSubview(collectionView)
    }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 10 // 示例数据数量
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CustomCell", for: indexPath) as! CustomCell
        let cellView = CustomCellView()
        cell.setView(view: cellView)
        return cell
    }

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        guard let cell = collectionView.cellForItem(at: indexPath) as? CustomCell,
              let view = cell.contentView.subviews.first as? CustomCellView else { return }
        let isOn = view.toggleSwitch.isOn

        // 在这里处理开关状态和indexPath的业务逻辑
        print("单元格\(indexPath.item)的开关状态：\(isOn)")
    }
}

方式二：抽取公共处理方法（推荐） #

由于didSelectItemAt原本用于处理单元格点击，将开关切换和单元格点击的逻辑抽成公共方法，更符合单一职责原则：

1. 在CustomVC中添加公共方法 #

class CustomVC: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
    // ... 其他代码不变

    private func handleCellSwitchAction(at indexPath: IndexPath, isSwitchOn: Bool) {
        // 统一处理开关状态和indexPath的逻辑
        print("单元格\(indexPath.item)的开关状态：\(isSwitchOn)")
    }

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        guard let cell = collectionView.cellForItem(at: indexPath) as? CustomCell,
              let view = cell.contentView.subviews.first as? CustomCellView else { return }
        // 点击单元格时也调用公共方法
        handleCellSwitchAction(at: indexPath, isSwitchOn: view.toggleSwitch.isOn)
    }
}

2. 修改CustomCellView的事件回调 #

@objc private func switchToggled() {
    var currentView: UIView? = self
    while let view = currentView {
        if let cell = view as? CustomCell {
            guard let collectionView = cell.superview as? UICollectionView,
                  let indexPath = collectionView.indexPath(for: cell),
                  let vc = collectionView.delegate as? CustomVC else { return }
            
            // 直接调用公共处理方法
            vc.handleCellSwitchAction(at: indexPath, isSwitchOn: toggleSwitch.isOn)
            break
        }
        currentView = view.superview
    }
}

内容的提问来源于stack exchange，提问作者KosFM