Custom Debug Window in visionOS

ContentView.swift

//
//  ContentView.swift
//  DebugWindow
//
//  Created by Yasuhito Nagatomo on 2023/11/25.
//

import SwiftUI
import RealityKit
import RealityKitContent

struct ContentView: View {
    #if DEBUG
    @Environment(DebugState.self) private var debugState
    #endif
    @State private var showImmersiveSpace = false
    @State private var immersiveSpaceIsShown = false

    @Environment(\.openImmersiveSpace) var openImmersiveSpace
    @Environment(\.dismissImmersiveSpace) var dismissImmersiveSpace

    let x = 100

    var body: some View {
        VStack {
            Model3D(named: "Scene", bundle: realityKitContentBundle)
                .padding(.bottom, 50)

            Text("Hello, world!")

            Toggle("Show Immersive Space", isOn: $showImmersiveSpace)
                .toggleStyle(.button)
                .padding(.top, 50)

            Button(action: {
                debugState.logger("new debug message.  x = \(x)")
            }, label: {
                Text("Add debug message (simple)")
            })
            .padding()

            Button(action: {
                debugState.logger2("new debug message.  x * 2 = \(x * 2)")
            }, label: {
                Text("Add debug message (file, line)")
            })
            .padding()
        }
        .padding()
        .onChange(of: showImmersiveSpace) { _, newValue in
            Task {
                if newValue {
                    switch await openImmersiveSpace(id: "ImmersiveSpace") {
                    case .opened:
                        immersiveSpaceIsShown = true
                    case .error, .userCancelled:
                        fallthrough
                    @unknown default:
                        immersiveSpaceIsShown = false
                        showImmersiveSpace = false
                    }
                } else if immersiveSpaceIsShown {
                    await dismissImmersiveSpace()
                    immersiveSpaceIsShown = false
                }
            }
        }
    }
}

#Preview(windowStyle: .automatic) {
    ContentView()
}

DebugPanelView.swift

//
//  DebugPanelView.swift
//  DebugWindow
//
//  Created by Yasuhito Nagatomo on 2023/11/25.
//

import SwiftUI

struct DebugPanelView: View {
    let debugState: DebugState

    var body: some View {
        VStack {
            Text("Debug Panel").font(.title).padding()

            Form {
                Section("Actions") {
                    Button(action: {}, label: { Text("Do something")})
                        .buttonStyle(.bordered)
                }
                Section("App Status") {
                    VStack {
                        Text("Status A: xxx")
                        Text("Status B: yyy")
                    }
                }
            }

            Text("Logs").font(.title3)
            ScrollView {
                VStack(alignment: .leading) {
                    ForEach(debugState.logs.reversed()) { log in
                        Text("\(log.number): \(log.message)")
                    }
                }
            }
            .padding()
            .background(.ultraThickMaterial,
                        in: RoundedRectangle(cornerRadius: 10))
            Spacer()
        }
        .padding()
    }
}

DebugState.swift

//
//  DebugState.swift
//  DebugWindow
//
//  Created by Yasuhito Nagatomo on 2023/11/25.
//

import Foundation

@Observable
final class DebugState {
    struct Log: Identifiable {
        var id: Int { number }
        let number: Int
        let message: String
    }
    var logs = [Log]()

    func logger(_ message: String) {
        logs.append(Log(number: logs.count, message: message))
    }

    func logger2(_ message: String,
                  function: String = #function, file: String = #file, line: Int = #line) {
        let url = URL(fileURLWithPath: file)
        let filename = url.lastPathComponent
        let thread = Thread.isMainThread ? "(m)" : "(-)"
        logger("\(filename): \(function): L\(line): T\(thread): " + message)
    }
}

DebugWindowApp.swift

//
//  DebugWindowApp.swift
//  DebugWindow
//
//  Created by Yasuhito Nagatomo on 2023/11/25.
//

import SwiftUI

@main
struct DebugWindowApp: App {
    @Environment(\.openWindow) private var openWindow
    #if DEBUG
    @State private var debugState = DebugState()
    #endif

    var body: some Scene {
        WindowGroup {
            ContentView()
            #if DEBUG
                .environment(debugState)
                .onAppear {
                    openWindow(id: "debug")
                }
            #endif
        }

        ImmersiveSpace(id: "ImmersiveSpace") {
            ImmersiveView()
        }

        #if DEBUG
        WindowGroup(id: "debug") {
            DebugPanelView(debugState: debugState)
        }
        .defaultSize(width: 400, height: 600)
        #endif
    }
}