swift-observable-uiviewrepresentable.swift

//
//  ContentView.swift
//  UnderstandSwiftUIChange
//
//  Created by Christian Selig on 2024-04-04.
//

import SwiftUI
import WebKit
import UIKit

struct ContentView: View {
    @State var viewModel: ViewModel = .init(url: URL(string: "https://apple.com")!)
    
    var body: some View {
        VStack {
            Text("Welcome to my cool View")
            WebPlayerView(viewModel: viewModel)
        }
        .onAppear {
            DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(5)) {
                viewModel = .init(url: URL(string: "https://christianselig.com")!)
            }
        }
        .onChange(of: viewModel) { oldValue, newValue in
            // IS called after change 🥳
            print("Changed to \(newValue.url) from \(oldValue.url)")
        }
    }
}

struct WebPlayerView: View {
    @State var viewModel: ViewModel
    
    var body: some View {
        ZStack {
            WebView(viewModel: viewModel)
        }
        .onChange(of: viewModel) { oldValue, newValue in
            // Not called after change 😥
            print("Our WebPlayerView changed from \(oldValue.url) to \(newValue.url)")
        }
    }
}

struct WebView: UIViewRepresentable {
    @State var viewModel: ViewModel
    
    func makeUIView(context: Context) -> some UIView {
        let webView = WKWebView()
        webView.load(URLRequest(url: viewModel.url))
        return webView
    }
    
    func updateUIView(_ uiView: UIViewType, context: Context) {
        // Not called after change 😥
        print("Update called on UIViewRepresentable, our URL is now \(viewModel.url)")
    }
}

@Observable
class ViewModel: NSObject {
    let url: URL
    
    init(url: URL) {
        self.url = url
    }
}