SwiftUI RealityKit Integration

TODO: collapasable, copyable, download, etc

MultipeerManager is a class that does networking. It sets some variables that I need to react to from UI views. If I start over, what is the best pattern to integrate that with a SwiftUI and RealityKit app? Spatial computing goes even further with visionOS updates that bring enhanced support for volumetric apps, powerful new enterprise APIs, the new TabletopKit framework, and more.

visionOS Highlights

TabletopKit Create collaborative experiences centered around a table. This new framework handles the manipulation of cards and pieces, establishing placement and layout, and defining game boards.

New enterprise APIs provide access to spatial barcode scanning, the Apple Neural Engine, object tracking parameters, and more.

visionOS for enterprise

Volumetric APIs • Create apps that take full advantage of depth and space — and can

run side by side with other apps in the Shared Space.
• Resize volumes by using the SwiftUI scene

modifier windowResizability.

Decide if you want the user’s hands to appear in front of or behind your digital content.

Inputs

Getting started? Explore the visionOS Pathway on developer.apple.com 􀯻

• Detect planes in all orientations. • Allow anchoring objects on surfaces in your surroundings.
• Use Room Anchors to consider the user’s surroundings on a

per-room basis.
• Attach content to individual objects around the user with the new

Object Tracking API for visionOS.

Updates to scene understanding

To integrate MultipeerManager with a SwiftUI and RealityKit app, you can leverage SwiftUI's reactive data flow and the Combine framework to observe changes in MultipeerManager and update the UI accordingly. Below are the steps and a sample implementation to guide you:

1. Define the MultipeerManager Class: Ensure your MultipeerManager class conforms to ObservableObject and publishes the variables you want the UI to react to.

2. Create a SwiftUI View Model: Create a view model that observes the MultipeerManager and bridges it to the SwiftUI view.

3. Update the SwiftUI View: Bind the view model's published properties to the SwiftUI view.

4. Integrate with RealityKit: Use the RealityKit components within your SwiftUI view and ensure they react to changes in the view model.

Step-by-Step Implementation

1. Define MultipeerManager Class

import Combine

class MultipeerManager: ObservableObject {
    @Published var connectedPeers: [String] = []
    @Published var receivedMessage: String = ""
    
    // Your networking logic here
    func connect() {
        // Connection logic
    }
    
    func sendMessage(_ message: String) {
        // Send message logic
    }
    
    // Other networking functions
}

2. Create a SwiftUI View Model

import SwiftUI
import Combine

class MultipeerViewModel: ObservableObject {
    @ObservedObject var manager = MultipeerManager()
    
    // Additional view-specific logic can go here
}

3. Update the SwiftUI View

import SwiftUI
import RealityKit

struct ContentView: View {
    @StateObject private var viewModel = MultipeerViewModel()
    
    var body: some View {
        VStack {
            Text("Connected Peers: \(viewModel.manager.connectedPeers.joined(separator: ", "))")
            Text("Received Message: \(viewModel.manager.receivedMessage)")
            
            // RealityKit View
            RealityView()
                .environmentObject(viewModel)
        }
        .onAppear {
            viewModel.manager.connect()
        }
    }
}

struct RealityView: View {
    @EnvironmentObject var viewModel: MultipeerViewModel
    
    var body: some View {
        RealityKitViewControllerRepresentable(viewModel: viewModel)
            .edgesIgnoringSafeArea(.all)
    }
}

struct RealityKitViewControllerRepresentable: UIViewControllerRepresentable {
    let viewModel: MultipeerViewModel
    
    func makeUIViewController(context: Context) -> RealityKitViewController {
        let controller = RealityKitViewController()
        controller.viewModel = viewModel
        return controller
    }
    
    func updateUIViewController(_ uiViewController: RealityKitViewController, context: Context) {
        // Update the UI Controller with new data
    }
}

class RealityKitViewController: UIViewController {
    var viewModel: MultipeerViewModel!
    var arView: ARView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        arView = ARView(frame: view.bounds)
        view.addSubview(arView)
        
        // Set up RealityKit scene
        setupScene()
    }
    
    func setupScene() {
        // RealityKit setup logic here
    }
}

Explanation

• MultipeerManager: This class handles networking and publishes any state changes using the @Published property wrapper, making it observable.
• MultipeerViewModel: This class observes MultipeerManager and exposes its properties to the SwiftUI view.
• ContentView: The main SwiftUI view, which displays information and contains the RealityKit view. It reacts to changes in MultipeerViewModel.
• RealityView & RealityKitViewControllerRepresentable: These are used to integrate RealityKit with SwiftUI. The RealityKitViewController sets up and manages the RealityKit scene.

This pattern ensures that your SwiftUI views and RealityKit components remain reactive to changes in the MultipeerManager, promoting a clean separation of concerns and leveraging SwiftUI's declarative nature.For RealityKit, I have several System that are called each frame. How could they work here?To integrate custom systems in RealityKit that are called each frame, you can extend the RealityKit setup in the RealityKitViewController by adding custom systems to the ARView. These systems can be used to perform custom per-frame updates.

Here’s a refined approach to include systems in the RealityKit setup while ensuring they work seamlessly with SwiftUI and the MultipeerManager.

Steps to Integrate Systems in RealityKit

1. Define Custom Systems: Create custom systems by conforming to the RealityKit.System protocol. These systems will execute logic every frame.

2. Register Systems in ARView: Register these custom systems with the ARView.

3. Integrate Systems with SwiftUI: Ensure the systems are aware of the MultipeerManager state changes.

Step-by-Step Implementation

1. Define Custom Systems

Create custom systems to handle per-frame updates.

import RealityKit

class CustomSystem: System {
    let viewModel: MultipeerViewModel

    init(viewModel: MultipeerViewModel) {
        self.viewModel = viewModel
    }

    func update(context: SceneUpdateContext) {
        // Custom per-frame logic here
        // Access viewModel.manager to react to MultipeerManager state changes
        let connectedPeers = viewModel.manager.connectedPeers
        let receivedMessage = viewModel.manager.receivedMessage
        // Example: Print state for debugging
        print("Connected Peers: \(connectedPeers)")
        print("Received Message: \(receivedMessage)")
    }
}

2. Register Systems in ARView

Update the RealityKitViewController to register the custom systems.

import SwiftUI
import RealityKit
import ARKit

class RealityKitViewController: UIViewController {
    var viewModel: MultipeerViewModel!
    var arView: ARView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        arView = ARView(frame: view.bounds)
        view.addSubview(arView)
        
        // Set up RealityKit scene
        setupScene()
        
        // Register custom systems
        arView.scene.addSystem(CustomSystem(viewModel: viewModel))
        // Add more systems as needed
    }
    
    func setupScene() {
        // RealityKit setup logic here
        let anchor = AnchorEntity(plane: .horizontal)
        arView.scene.addAnchor(anchor)
        
        // Example: Adding an entity to the scene
        let box = MeshResource.generateBox(size: 0.1)
        let material = SimpleMaterial(color: .blue, isMetallic: false)
        let modelEntity = ModelEntity(mesh: box, materials: [material])
        anchor.addChild(modelEntity)
    }
}

3. Update SwiftUI Integration

Ensure the SwiftUI view properly integrates with the updated RealityKitViewController.

struct ContentView: View {
    @StateObject private var viewModel = MultipeerViewModel()
    
    var body: some View {
        VStack {
            Text("Connected Peers: \(viewModel.manager.connectedPeers.joined(separator: ", "))")
            Text("Received Message: \(viewModel.manager.receivedMessage)")
            
            // RealityKit View
            RealityView()
                .environmentObject(viewModel)
        }
        .onAppear {
            viewModel.manager.connect()
        }
    }
}

struct RealityView: View {
    @EnvironmentObject var viewModel: MultipeerViewModel
    
    var body: some View {
        RealityKitViewControllerRepresentable(viewModel: viewModel)
            .edgesIgnoringSafeArea(.all)
    }
}

struct RealityKitViewControllerRepresentable: UIViewControllerRepresentable {
    let viewModel: MultipeerViewModel
    
    func makeUIViewController(context: Context) -> RealityKitViewController {
        let controller = RealityKitViewController()
        controller.viewModel = viewModel
        return controller
    }
    
    func updateUIViewController(_ uiViewController: RealityKitViewController, context: Context) {
        // Update the UI Controller with new data if necessary
    }
}

Explanation

• CustomSystem: A custom system that conforms to the RealityKit.System protocol and performs per-frame updates. It accesses the viewModel to react to MultipeerManager state changes.
• RealityKitViewController: Registers the custom systems to ARView and sets up the RealityKit scene.
• SwiftUI Integration: Integrates the RealityKit view with SwiftUI, ensuring the viewModel is passed correctly and updates are handled.

This approach ensures that your custom systems are integrated into the RealityKit scene and can react to changes in the MultipeerManager state, while maintaining a clean and reactive SwiftUI interface.

SwiftUI RealityKit Integration created at Tue Jan 20 1970 21:17:23 GMT+0000 (Coordinated Universal Time)