I want to use a Combine in my project and face the problem. Here is the code of the ViewController

import Combine
import UIKit

class ProfileDetailsController: ViewController {
    //

    // MARK: - Views
    @IBOutlet private var tableView: UITableView!

    // MARK: - Properties
    private typealias DataSource = UITableViewDiffableDataSource<ProfileDetailsSection, ProfileDetailsRow>
    private typealias Snapshot = NSDiffableDataSourceSnapshot<ProfileDetailsSection, ProfileDetailsRow>

    @Published private var data: [ProfileDetailsSectionModel] = {
        return ProfileDetailsSection.allCases.map { ProfileDetailsSectionModel(section: $0, data: $0.rows) }
    }()
    
    private lazy var dataSource: DataSource = {
        let dataSource = DataSource(tableView: tableView) { tableView, _, model in
            let cell = tableView.dequeueReusableCell(withIdentifier: TextFieldTableCell.name) as! TextFieldTableCell
            cell.delegate = self
            cell.setData(model: model)
            return cell
        }
        dataSource.defaultRowAnimation = .fade
        return dataSource
    }()
}

// MARK: - Setup binding
extension ProfileDetailsController {
    override func setupBinding() {
        tableView.registerCellXib(cell: TextFieldTableCell.self)
        $data.receive(on: RunLoop.main).sink { [weak self] models in
            let sections = models.map { $0.section }
            var snapshot = Snapshot()
            snapshot.appendSections(sections)
            models.forEach { snapshot.appendItems($0.data, toSection: $0.section) }
            self?.dataSource.apply(snapshot, animatingDifferences: true)
        }.store(in: &cancellable)
    }
}

// MARK: - Cell delegates
extension ProfileDetailsController: TextFieldTableCellDelegate {
    func switcherAction() { }
}

And here is the code of the cell.

import UIKit

protocol TextFieldTableCellData {
    var placeholder: String? { get }
}

protocol TextFieldTableCellDelegate: NSObjectProtocol {
    func switcherAction()
}

class TextFieldTableCell: TableViewCell {
    //

    // MARK: - Views
    @IBOutlet private var textField: ZWTextField!

    // MARK: - Properties
    public weak var delegate: TextFieldTableCellDelegate?

    override class var height: CGFloat {
        return 72
    }
}

// MARK: - Public method
extension TextFieldTableCell {
    func setData(model: TextFieldTableCellData) {
        textField.placeholder = model.placeholder
    }
}

ViewController's deinit was not called. But when I use this code for ViewController

import UIKit

class ProfileDetailsController: ViewController {
    //

    // MARK: - Views
    @IBOutlet private var tableView: UITableView!

    // MARK: - Properties
    @Published private var data: [ProfileDetailsSectionModel] = {
        return ProfileDetailsSection.allCases.map { ProfileDetailsSectionModel(section: $0, data: $0.rows) }
    }()
}

// MARK: - Startup
extension ProfileDetailsController {
    override func startup() {
        tableView.dataSource = self
        tableView.registerCellXib(cell: TextFieldTableCell.self)
    }
}

// MARK: - Startup
extension ProfileDetailsController: UITableViewDataSource {
    func numberOfSections(in tableView: UITableView) -> Int {
        return data.count
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return data[section].data.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let model = data[indexPath.section].data[indexPath.row]
        let cell = tableView.dequeueReusableCell(withIdentifier: TextFieldTableCell.name) as! TextFieldTableCell
        cell.delegate = self
        cell.setData(model: model)
        return cell
    }
}

// MARK: - Cell delegates
extension ProfileDetailsController: TextFieldTableCellDelegate {
    func switcherAction() {}
}

Everything is fine. deinit called. I tried to set dataSource optional and set it nil on deinit, the same result. With Combine deinit called only when I comment this line:

cell.delegate = self

Does anyone know what's the matter? Xcode 13.2 iOS 15.2

CodePudding user response：

The Combine stuff is a total red herring. That's why you can't locate the problem; you're looking in the wrong place. The issue is the difference between an old-fashioned data source and a diffable data source. The problem is here:

private lazy var dataSource: DataSource = { // *
    let dataSource = DataSource(tableView: tableView) { tableView, _, model in
        let cell = tableView.dequeueReusableCell(withIdentifier: TextFieldTableCell.name) as! TextFieldTableCell
        cell.delegate = self // *

I've starred the problematic lines:

• On the one hand, you (self, the view controller) are retaining the dataSource.

• On the other hand, you are giving the data source a cell provider function in which you speak of self.

That's a retain cycle! You need to break that cycle. Change

let dataSource = DataSource(tableView: tableView) { tableView, _, model in

To

let dataSource = DataSource(tableView: tableView) { [weak self] tableView, _, model in

(That will compile, because although self is now an Optional, so is cell.delegate.)