---
title: "Discover the Spatial Preview framework"
description: "Use Spatial Preview to send Mac app documents and live USDKit stages to Quick Look on visionOS with device discovery, sync, editing, and review tools."
shoutout: "Unofficial, made with love by Superwall - the best way to monetize your apps."
category: "Spatial Computing"
---

# Discover the Spatial Preview framework


[Watch on Apple Developer](https://developer.apple.com/videos/play/wwdc2026/282/)

Use Spatial Preview to send Mac app documents and live USDKit stages to Quick Look on visionOS with device discovery, sync, editing, and review tools.

## TL;DR

- Spatial Preview lets macOS apps share content to Apple Vision Pro through Mac Virtual Display or a device picker; Quick Look on visionOS presents the content and no visionOS app code is required.
- DocumentPreviewSession is for files such as Apple Immersive Video frames, spatial photos, PDFs, images, and other documents; updateContents(url:) swaps content within an existing scene.
- USDPreviewSession shares a live USDKit USDStage for 3D review and editing, with built-in camera viewpoints, material overrides, immersive viewing, annotations, object manipulation, variants, export, and playback events.
- Spatial Preview optimizes USD assets by default for visionOS performance; apps can opt out with .unmodified but must handle unshareable complex assets.

## What Spatial Preview provides

Spatial Preview is a macOS framework for extending content from a Mac app into visionOS. A Mac app selects a SpatialPreviewEndpoint, creates a preview session, and starts it; Quick Look launches on Apple Vision Pro and displays the provided content.

The framework supports two main session types: DocumentPreviewSession for file-based content and USDPreviewSession for live 3D content backed by a USDKit stage. The session is driven from macOS, so adopting it does not require writing a visionOS companion app.

- Use the currently connected Mac Virtual Display endpoint when available.
- Use SpatialPreviewDevicePicker to let people choose a nearby Apple Vision Pro on the same iCloud account.
- Use DocumentPreviewSession for spatial media, PDFs, images, and other supported files.
- Use USDPreviewSession for 3D scenes represented as USD.

## Document Preview workflows

Document Preview is the lightweight path for sharing files from a Mac app to visionOS. The session starts on a chosen endpoint, then the app provides a content URL that Quick Look displays. The session example uses Apple Immersive Video frames, but the same pattern applies to spatial photos, PDFs, standard images, files, and supported 3D content.

For gallery-like experiences, reuse the same DocumentPreviewSession and call updateContents(url:) to replace the displayed file in place. Creating a new session and calling start again opens a new scene instead of updating the existing one.

- Create a ConnectedSpatialEndpointObserver to obtain an endpoint from Mac Virtual Display.
- Create DocumentPreviewSession with a display name and content type.
- Start the session, then call updateContents(url:) with the file URL.
- Observe session.state to detect invalidation when the scene is closed on visionOS.
- Call close() when finished to end the session and dismiss the scene.

### Start a document preview and show the device picker

Integrates endpoint selection into a SwiftUI macOS app, then starts a DocumentPreviewSession and sends a file to Quick Look on visionOS.

```swift
import SwiftUI
import SpatialPreview

let deviceObserver = ConnectedSpatialEndpointObserver()
let previewSession = DocumentPreviewSession(name: "Immersive.aivu", contentType: .aivu)

func startPreview(contentURL: URL, endpoint: SpatialPreviewEndpoint) async throws {
    try await previewSession.start(endpoint: endpoint)
    try await previewSession.updateContents(url: contentURL)
}

@State var showDevicePicker = false

var body: some View {
    // ...
    .sheet(isPresented: $showDevicePicker) {
        SpatialPreviewDevicePicker(isPresented: $showDevicePicker) { endpoint in
            showDevicePicker = false
            Task { try await startPreview(contentURL: contentURL, endpoint: endpoint) }
        }
    }
}
```

### Update an existing document preview session

Uses updateContents(url:) to swap files within the same launched scene, observes invalidation, and closes the session when done.

```text
ForEach(contentURLs, id: \.self) { url in
    Button {
        Task { try await previewSession?.updateContents(url: url) }
    }
}
.task(id: previewSession.map { ObjectIdentifier($0) }) {
    for await state in Observations({ session.state }) {
        if state.isInvalidated {
            previewSession = nil
            break
        }
    }
}

try await previewSession?.close()
```

## USD Preview for live 3D content

USD Preview shares a USDKit stage from a macOS app to visionOS. When the USDPreviewSession starts, the content appears in a bounded 3D view and can be opened immersively at full scale. Quick Look provides built-in 3D review features such as navigating scene cameras and applying material overrides like wireframe mode.

Spatial Preview automatically optimizes USD content before sharing to help it perform on Apple Vision Pro. Optimization can include mesh decimation, texture downsampling, and potentially full scene reconstruction. Reconstructed scenes may be viewable and annotatable but not editable.

- Open USD content with USDKit as a USDStage.
- Create USDPreviewSession(stage:) and start it on the chosen SpatialPreviewEndpoint.
- Use the default optimized path for complex assets unless exact unmodified sharing is required.
- If using .unmodified, handle USDPreviewSession.Error.assetUnshareable when the asset is too complex to share.

### Start a USD preview session

Loads a USD asset with USDKit, creates a live USDPreviewSession, and shares it to the selected Vision Pro endpoint.

```swift
import SpatialPreview
import USDKit

let deviceObserver = ConnectedSpatialEndpointObserver()
var usdSession: USDPreviewSession?

func shareStage(to endpoint: SpatialPreviewEndpoint) async throws {
    let stageURL = Bundle.main.url(forResource: "sampleScene", withExtension: "usdz")!
    let stage = try USDStage.open(stageURL)
    usdSession = USDPreviewSession(stage: stage)
    try await usdSession?.start(endpoint: endpoint)
}
```

### Request unmodified USD sharing

Opts out of Spatial Preview optimization and handles the error case for assets that cannot be shared as-is.

```text
do {
    try await usdSession.start(endpoint: endpoint, parameters: .unmodified)
} catch USDPreviewSession.Error.assetUnshareable {
    // Handle Asset Unshareable error
}
```

## Live USD editing and Quick Look features

A USDPreviewSession uses a live USD stage to synchronize edits between macOS and visionOS. Changes made with normal USDKit APIs on the Mac are reflected in Quick Look, and supported edits made in Quick Look are reflected back into the stage.

The session demonstrates variants for changing furniture layout, annotations represented as USD data, and object manipulation controlled by metadata. Annotations appear on visionOS when they are children of the document annotation group, and gesture manipulation requires the target prims to be marked spatially editable.

- Use USD variant sets to switch between alternative scene data such as layout positions and rotations.
- Observe UsdStage.ObjectsDidChange to react to edits arriving from visionOS.
- Use AppleTextAnnotation-style data for text, author, and a stable identifier when modeling annotations.
- Set apple.spatialEditable metadata on prims that should be moveable with gestures in Quick Look.
- Preview on macOS can help configure spatial-editable metadata on USD assets.

### Apply a layout variant with USDKit

Changes a USD variant selection in the macOS app; the live stage synchronizes the resulting layout to visionOS.

```swift
func applyLayoutVariant(named layoutVariantName: String) throws {
    let prim = stage.prim(at: SdfPath("/root/furniture"))
    try prim.variantSets?.setSelection("Layout", variantName: layoutVariantName)
}
```

### Observe USD changes and enable manipulation metadata

Listens for synchronized stage changes, such as annotations from Quick Look, and shows the metadata required for gesture-based object manipulation.

```swift
observerToken = stage.addObserver(for: UsdStage.ObjectsDidChange.self) { notice in
    for path in notice.resyncedPaths {
        let prim = notice.stage.prim(at: path)
        guard prim.isValid else { continue }
        if prim.isAnnotation {
            // Handle annotation change
            break
        }
    }
}

// Metadata required for object manipulation in Quick Look:
// customData = { dictionary apple = { bool spatialEditable = 1 } }
```

## Session options, events, progress, and next steps

USDPreviewSession exposes configurable Quick Look features and non-USD session events. By default, annotations, object manipulation, and USD export are enabled; apps can also pass explicit options at start time. Event streams can report animation playback changes, and observable progress can drive loading UI while large assets synchronize.

For new integrations, Apple recommends using the USDKit Swift APIs directly with Spatial Preview. Existing USD-based Mac apps can bridge their USD implementation to USDKit to transfer edits. Related follow-up topics include USDKit, OpenUSD fundamentals, asset rendering-cost reduction on visionOS, and collaborative structured 3D model workflows.

- Start USD sessions with options such as .annotations, .perObjectManipulation, and .export when customizing available Quick Look tools.
- Listen to session.events for timeChanged and playbackStateChanged to keep Mac-side playback UI synchronized.
- Observe session.progress.fractionCompleted to display transfer or synchronization progress.
- SharePlay support on visionOS allows collaborators to join the same live review and editing session.

### Configure USD session options and listen for playback events

Controls Quick Look editing features and synchronizes animation state back to the macOS app.

```swift
try await session.start(endpoint: endpoint, options: [.annotations, .perObjectManipulation, .export])

func listenForEvents(session: USDPreviewSession) async {
    for await event in session.events {
        if case .timeChanged(let time) = event {
            playbackModel.timeCode = time
        } else if case .playbackStateChanged(let isPlaying) = event {
            playbackModel.playbackStateChanged(isPlaying)
        }
    }
}
```

### Observe sharing progress

Displays progress in the Mac UI while USD content is synchronized to Apple Vision Pro.

```text
@State private var sessionProgress: Double = 0

.task(id: usdSession.map { ObjectIdentifier($0) }) {
    guard let session = usdSession else { return }
    for await fraction in Observations({ session.progress.fractionCompleted }) {
        sessionProgress = fraction
    }
}
.overlay(alignment: .bottom) {
    ProgressView(value: sessionProgress).padding()
}
```

## Resources

- [Reducing the rendering cost of RealityKit content on visionOS](https://developer.apple.com/documentation/visionOS/reducing-the-rendering-cost-of-RealityKit-content-on-visionOS)
- [Spatial Preview](https://developer.apple.com/documentation/SpatialPreview)

## Related Sessions

- [Collaborate on structured 3D models in visionOS](https://wwdc.ai/2026/284)
- [Discover USDKit and what's new in OpenUSD](https://wwdc.ai/2026/285)
- [Understand USD fundamentals](https://developer.apple.com/videos/play/wwdc2022/10129)

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