RIBs+SwiftUI

HomeInteractor.swift

import RIBs
import RxSwift

protocol HomeRouting: ViewableRouting {}

protocol HomePresentable: Presentable {
    var listener: HomePresentableListener? { get set }
    func update(state: HomeViewState)
}

protocol HomeListener: AnyObject {}

final class HomeInteractor: PresentableInteractor<HomePresentable>, HomeInteractable, HomePresentableListener {
    weak var router: HomeRouting?
    weak var listener: HomeListener?

    override init(presenter: HomePresentable) {
        super.init(presenter: presenter)
        presenter.listener = self
    }
    
    func request(action: HomeViewAction) {
        let state: HomeViewState
        switch action {
        case .viewDidLoad:
            state = .init(title: "ViewDidLoad Action",
                          desc: "Number \(Int.random(in: 0 ... 5))")
        case .tap1:
            state = .init(title: "Tap1 Action",
                          desc: "Tap1 Number \(Int.random(in: 0 ... 5))")
        case .tap2:
            state = .init(title: "Tap2 Action",
                          desc: "Tap2 Number \(Int.random(in: 0 ... 5))")
        }
        presenter.update(state: state)
    }
}

HomeView.swift

import Foundation
import SwiftUI

class HomeViewModel: ObservableObject {
    typealias State = HomeViewState
    typealias Action = HomeViewAction

    weak var listener: HomePresentableListener?

    @Published var state: State

    init(listener: HomePresentableListener? = nil,
         state: State)
    {
        self.listener = listener
        self.state = state
    }

    func update(state: State) {
        self.state = state
    }

    func request(action: Action) {
        listener?.request(action: action)
    }
}

struct HomeView: View {
    @ObservedObject var viewModel: HomeViewModel

    var body: some View {
        HStack {
            Spacer()
            VStack(alignment: .center) {
                Spacer()

                Button("Tap1 Action Button") {
                    viewModel.request(action: .tap1)
                }
                
                Button("Tap2 Action Button") {
                    viewModel.request(action: .tap2)
                }

                Spacer()
                    .frame(height: 10)

                Text(viewModel.state.title)
                    .onChange(of: viewModel.state.title) { _ in
                        print("title changed to \(viewModel.state.desc)!")
                    }
                    .font(.title)
                    .border(.gray)

                Spacer()
                    .frame(height: 10)

                Text(viewModel.state.desc)
                    .onChange(of: viewModel.state.desc) { _ in
                        print("desc changed to \(viewModel.state.desc)!")
                    }
                    .font(.title)
                    .border(.gray)

                Spacer()
            }
            Spacer()
        }
        .border(Color.blue)
        .padding()
    }
}

#if DEBUG
struct HomeView_Previews: PreviewProvider {
    typealias State = HomeViewState
    typealias Action = HomeViewAction
    typealias ViewModel = HomeViewModel

    class Listener: HomePresentableListener {
        var viewModel: ViewModel? {
            didSet { viewModel?.listener = self }
        }

        func request(action: Action) {
            let state: State
            switch action {
            case .viewDidLoad:
                state = .init(title: "Preview ViewDidLoad Action",
                              desc: "Number \(Int.random(in: 0 ... 5))")
            case .tap1:
                state = .init(title: "Preview Tap1 Action",
                              desc: "Tap1 Number \(Int.random(in: 0 ... 5))")
            case .tap2:
                state = .init(title: "Preview Tap2 Action",
                              desc: "Tap2 Number \(Int.random(in: 0 ... 5))")
            }
            viewModel?.update(state: state)
        }
    }
    
    static let listener = Listener()
    
    static var previews: some View {
        let state = State(title: "Hello", desc: "World")
        let view = HomeView(viewModel: .init(state: state))
        listener.viewModel = view.viewModel
        
        return view
    }
}
#endif

HomeViewController.swift

import UIKit
import SwiftUI

protocol HomePresentableListener: AnyObject {
    func request(action: HomeViewAction)
}

final class HomeViewController: UIViewController, HomePresentable, HomeViewControllable {
    weak var listener: HomePresentableListener? {
        didSet {
            viewModel.listener = listener
        }
    }
    
    let viewModel = HomeViewModel(state: .init(title: "Hello", desc: "World"))
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        title = "Hello World"
        
        HomeView(viewModel: viewModel)
            .attachTo(ViewController: self)
        
        listener?.request(action: .viewDidLoad)
    }
    
    public func update(state: HomeViewState) {
        viewModel.update(state: state)
    }
}

extension View {
    func attachTo(ViewController parentViewController: UIViewController) {
        let contentVC = UIHostingController(rootView: self)
        let parentVC = parentViewController

        parentVC.addChild(contentVC)
        contentVC.view.translatesAutoresizingMaskIntoConstraints = false
        parentVC.view.addSubview(contentVC.view)
        contentVC.didMove(toParent: parentVC)
        
        NSLayoutConstraint.activate([
            contentVC.view.topAnchor.constraint(equalTo: parentVC.view.topAnchor),
            contentVC.view.bottomAnchor.constraint(equalTo: parentVC.view.bottomAnchor),
            contentVC.view.leadingAnchor.constraint(equalTo: parentVC.view.leadingAnchor),
            contentVC.view.trailingAnchor.constraint(equalTo: parentVC.view.trailingAnchor),
        ])
    }
}

HomeViewStateAction.swift

import Foundation

struct HomeViewState {
    var title: String
    var desc: String
}

enum HomeViewAction {
    case viewDidLoad
    case tap1
    case tap2
}