如何使用 SwiftUI 视图代替表格视图单元格

Question

如何使用 SwiftUI 视图结构代替 UITableViewController 中的传统单元格和 xib？

import UIKit
import SwiftUI

class MasterViewController: UITableViewController {

    var detailViewController: DetailViewController? = nil
    var objects = [Any]()

    // MARK: - View Lifecycle
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        navigationItem.title = "Table View"

        //...
    }



    // MARK: - Table View Methods

    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return objects.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCell(MySwiftUIView())

        // ...
        return cell
    }
} ...

问题很明显，因为 UIHostedController SwiftUI 视图不是表格单元格，但我怎么能像使用它一样使用它呢？

Answer 1

对答案进行幻灯片修改以修复内存泄漏，因为他们仅将托管控制器添加为子级，但从未将其删除。

final class HostingTableViewCell<Content: View>: UITableViewCell {
    private let hostingController = UIHostingController<Content?>(rootView: nil)
    
    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        hostingController.view.backgroundColor = .clear
    }
    
    private func removeHostingControllerFromParent() {
        hostingController.willMove(toParent: nil)
        hostingController.view.removeFromSuperview()
        hostingController.removeFromParent()
    }
    
    deinit {
        // remove parent
        removeHostingControllerFromParent()
    }
    
    @available(*, unavailable)
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func set(rootView: Content, parentController: UIViewController) {
        hostingController.rootView = rootView
        hostingController.view.invalidateIntrinsicContentSize()
        
        let requiresControllerMove = hostingController.parent != parentController
        if requiresControllerMove {
            // remove old parent if exists
            removeHostingControllerFromParent()
            parentController.addChild(hostingController)
        }
        
        if !contentView.subviews.contains(hostingController.view) {
            contentView.addSubview(hostingController.view)
            hostingController.view.translatesAutoresizingMaskIntoConstraints = false
            hostingController.view.leadingAnchor.constraint(equalTo: contentView.leadingAnchor).isActive = true
            hostingController.view.trailingAnchor.constraint(equalTo: contentView.trailingAnchor).isActive = true
            hostingController.view.topAnchor.constraint(equalTo: contentView.topAnchor).isActive = true
            hostingController.view.bottomAnchor.constraint(equalTo: contentView.bottomAnchor).isActive = true
        }
        
        if requiresControllerMove {
            hostingController.didMove(toParent: parentController)
        }
    }
}

Answer 2

感谢您在这里回答您自己的问题。您的解决方案帮助我制作了一个通用的 HostingTableViewCell 类。如果有人像我一样在谷歌上发现这个问题，我会在这里发布。

import SwiftUI

class HostingTableViewCell<Content: View>: UITableViewCell {

    private weak var controller: UIHostingController<Content>?

    func host(_ view: Content, parent: UIViewController) {
        if let controller = controller {
            controller.rootView = view
            controller.view.layoutIfNeeded()
        } else {
            let swiftUICellViewController = UIHostingController(rootView: view)
            controller = swiftUICellViewController
            swiftUICellViewController.view.backgroundColor = .clear
            
            layoutIfNeeded()
            
            parent.addChild(swiftUICellViewController)
            contentView.addSubview(swiftUICellViewController.view)
            swiftUICellViewController.view.translatesAutoresizingMaskIntoConstraints = false
            contentView.addConstraint(NSLayoutConstraint(item: swiftUICellViewController.view!, attribute: NSLayoutConstraint.Attribute.leading, relatedBy: NSLayoutConstraint.Relation.equal, toItem: contentView, attribute: NSLayoutConstraint.Attribute.leading, multiplier: 1.0, constant: 0.0))
            contentView.addConstraint(NSLayoutConstraint(item: swiftUICellViewController.view!, attribute: NSLayoutConstraint.Attribute.trailing, relatedBy: NSLayoutConstraint.Relation.equal, toItem: contentView, attribute: NSLayoutConstraint.Attribute.trailing, multiplier: 1.0, constant: 0.0))
            contentView.addConstraint(NSLayoutConstraint(item: swiftUICellViewController.view!, attribute: NSLayoutConstraint.Attribute.top, relatedBy: NSLayoutConstraint.Relation.equal, toItem: contentView, attribute: NSLayoutConstraint.Attribute.top, multiplier: 1.0, constant: 0.0))
            contentView.addConstraint(NSLayoutConstraint(item: swiftUICellViewController.view!, attribute: NSLayoutConstraint.Attribute.bottom, relatedBy: NSLayoutConstraint.Relation.equal, toItem: contentView, attribute: NSLayoutConstraint.Attribute.bottom, multiplier: 1.0, constant: 0.0))
        
            swiftUICellViewController.didMove(toParent: parent)
            swiftUICellViewController.view.layoutIfNeeded()
        }
    }
}

在你的 UITableViewController 中：

override func viewDidLoad() {
    super.viewDidLoad()
    tableView.register(HostingTableViewCell<Text>.self, forCellReuseIdentifier: "textCell")
}

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "textCell") as! HostingTableViewCell<Text>
    cell.host(Text("Yay!"), parent: self)
    return cell
}

如果人们似乎使用它，可能会将它变成一个包。