In iOS 16, Apple added UIHostingConfiguration, making it straightforward to use a SwiftUI view in instances of UICollectionViewCell and UITableViewCell. This project shows how UIHostingConfiguration can be backported to iOS 14 by implementing a type that conforms to the UIContentConfiguration protocol.

SwiftUIHostingConfiguration.md

SwiftUIHostingConfiguration

In iOS 16, Apple added UIHostingConfiguration, making it straightforward to use a SwiftUI view in instances of UICollectionViewCell and UITableViewCell. This gist shows how UIHostingConfiguration can be backported to iOS 14 by implementing a type that conforms to UIContentConfiguration.

Starting from iOS 16, we can use SwiftUI views in an instance of UICollectionView or UITableViewCell like this:

cell.contentConfiguration = UIHostingConfiguration {
    ExampleCellContentView(color: Color(item.color), text: item.text)
}

With the SwiftUIHostingConfiguration, we can use a similar API starting from iOS 14.

cell.contentConfiguration = SwiftUIHostingConfiguration(parentViewController: self) {
    ExampleCellContentView(color: Color(item.color), text: item.text)
}

We pass an instance of our view controller because, under the hood, the SwiftUIHostingConfiguration creates a UIHostingController and inserts it into the view controller hierarchy.

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SwiftUIHostingConfiguration.swift

import SwiftUI
import UIKit

struct SwiftUIHostingConfiguration<Content: View>: UIContentConfiguration {
    private weak var parentViewController: UIViewController?
    private let content: Content

    init(parentViewController: UIViewController, @ViewBuilder content: () -> Content) {
        self.parentViewController = parentViewController
        self.content = content()
    }

    private init(parentViewController: UIViewController, content: Content) {
        self.parentViewController = parentViewController
        self.content = content
    }

    func makeContentView() -> any UIView & UIContentView {
        let contentView = ContentView(configuration: self)
        contentView.layoutMargins = .zero
        return contentView
    }
    
    func updated(for state: any UIConfigurationState) -> SwiftUIHostingConfiguration {
        guard let parentViewController else {
            fatalError("Cannot update \(self) because parentViewController has been deallocated")
        }
        return SwiftUIHostingConfiguration(parentViewController: parentViewController, content: content)
    }
}

private extension SwiftUIHostingConfiguration {
    final class ContentView: UIView, UIContentView {
        var configuration: UIContentConfiguration {
            get {
                currentConfiguration
            }
            set {
                guard let newConfiguration = newValue as? SwiftUIHostingConfiguration<Content> else {
                    fatalError("Expected configuration to be of type \(SwiftUIHostingConfiguration<Content>.self)")
                }
                currentConfiguration = newConfiguration
                hostingController.rootView = newConfiguration.content
                // Removing and re-adding the hosting controller from the view hierarchy and then invalidating
                // the intrinsic content size seems to be the only way to cause the UICollectionVIew and
                // UITableView to relayout the cells and update the heights.
                removeHostingControllerFromViewHierarchy()
                addHostingControllerToViewHierarchy()
                invalidateIntrinsicContentSize()
            }
        }

        private let hostingController: UIHostingController<Content>
        private var currentConfiguration: SwiftUIHostingConfiguration<Content>

        init(configuration: SwiftUIHostingConfiguration<Content>) {
            self.hostingController = UIHostingController(rootView: configuration.content)
            self.currentConfiguration = configuration
            super.init(frame: .zero)
            addHostingControllerToViewHierarchy()
        }

        required init?(coder: NSCoder) {
            fatalError("init(coder:) has not been implemented")
        }

        deinit {
            removeHostingControllerFromViewHierarchy()
        }

        func supports(_ configuration: any UIContentConfiguration) -> Bool {
            configuration is SwiftUIHostingConfiguration<Content>
        }
    }
}

private extension SwiftUIHostingConfiguration.ContentView {
    private func addHostingControllerToViewHierarchy() {
        guard let parentViewController = currentConfiguration.parentViewController else {
            fatalError("Cannot setup \(Self.self) as parentViewController has been deallocated")
        }
        parentViewController.addChild(hostingController)
        hostingController.view.translatesAutoresizingMaskIntoConstraints = false
        addSubview(hostingController.view)
        NSLayoutConstraint.activate([
            hostingController.view.leadingAnchor.constraint(equalTo: layoutMarginsGuide.leadingAnchor),
            hostingController.view.trailingAnchor.constraint(equalTo: layoutMarginsGuide.trailingAnchor),
            hostingController.view.topAnchor.constraint(equalTo: layoutMarginsGuide.topAnchor),
            hostingController.view.bottomAnchor.constraint(equalTo: layoutMarginsGuide.bottomAnchor)
        ])
        hostingController.didMove(toParent: parentViewController)
    }

    private func removeHostingControllerFromViewHierarchy() {
        hostingController.willMove(toParent: nil)
        hostingController.view.removeFromSuperview()
        hostingController.removeFromParent()
    }
}