Spatial Preview Framework

import SwiftUI
import SpatialPreview

struct ImmersiveGalleryView: View {
    // URLs of Apple Immersive Video frame files on disk
    let frameURLs: [URL]

    @State private var session: DocumentPreviewSession?
    @State private var endpoint: SpatialPreviewEndpoint?
    @State private var showDevicePicker = false
    @State private var sessionInvalidated = false

    var body: some View {
        VStack(spacing: 16) {
            Text("Immersive Rendering Gallery")
                .font(.headline)

            if session == nil {
                Button("Start Spatial Preview") {
                    Task { await startSession() }
                }
                Button("Pick Vision Pro Device") {
                    showDevicePicker = true
                }
            } else {
                ForEach(Array(frameURLs.enumerated()), id: \.offset) { index, url in
                    Button("Frame \(index + 1)") {
                        Task { await swapFrame(to: url) }
                    }
                }
                Button("Close Session", role: .destructive) {
                    session?.close()
                    session = nil
                }
            }

            if sessionInvalidated {
                Text("Session closed on Vision Pro.")
                    .foregroundStyle(.secondary)
            }
        }
        .padding()
        .sheet(isPresented: $showDevicePicker) {
            SpatialPreviewDevicePickerView { picked in
                endpoint = picked
                showDevicePicker = false
                Task { await startSession() }
            }
        }
        .task {
            // Observe the Mac Virtual Display connected endpoint
            let observer = ConnectedSpatialEndpointObserver()
            for await connectedEndpoint in observer.endpoints {
                endpoint = connectedEndpoint
            }
        }
    }

    private func startSession() async {
        guard let endpoint, let firstURL = frameURLs.first else { return }
        let newSession = DocumentPreviewSession(
            documentType: .immersiveVideoFrame,
            name: "Rendering Gallery"
        )
        do {
            try await newSession.start(on: endpoint, contentURL: firstURL)
            session = newSession
            observeSessionState(newSession)
        } catch {
            print("Failed to start session: \(error)")
        }
    }

    private func swapFrame(to url: URL) async {
        do {
            try await session?.updateContents(contentURL: url)
        } catch {
            print("Failed to update contents: \(error)")
        }
    }

    private func observeSessionState(_ s: DocumentPreviewSession) {
        Task {
            for await state in s.stateUpdates {
                if state == .invalidated {
                    sessionInvalidated = true
                    session = nil
                }
            }
        }
    }
}