UIKit+SwiftUI.swift

import UIKit
import SwiftUI

struct MyView: View {
    @State var number: Int = .zero
    
    var body: some View {
        MyViewController.SwiftUIView(number: $number)
    }
}

final class MyViewController: UIViewController {
    protocol Delegate: AnyObject {
        func set(number: Int)
    }
    
    var number: Int {
        didSet {
            guard oldValue != number else { return }
        }
    }
    
    weak var delegate: Delegate?
    
    init(number: Int) {
        self.number = number
        super.init(nibName: nil, bundle: nil)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func increment() {
        number += 1
        delegate?.set(number: number)
    }
}

extension MyViewController {
    struct SwiftUIView: UIViewControllerRepresentable {
        @Binding var number: Int
        
        func makeUIViewController(context: Context) -> MyViewController {
            let vc = MyViewController(number: number)
            vc.delegate = context.coordinator
            return vc
        }
        
        func updateUIViewController(_ uiViewController: MyViewController, context: Context) {
            context.coordinator.number = _number
            uiViewController.delegate = context.coordinator
            uiViewController.number = number
        }
        
        func makeCoordinator() -> Coordinator {
            .init(number: $number)
        }
        
        final class Coordinator: Delegate {
            var number: Binding<Int>
            
            init(number: Binding<Int>) {
                self.number = number
            }
            
            func set(number: Int) {
                self.number.wrappedValue = number
            }
        }
    }
}