# Preview(_:traits:body:) Preview an NSViewController. ``` @freestanding(declaration) macro Preview(_ name: String? = nil, traits: PreviewTrait..., @PreviewMacroBodyBuilder body: @escaping @MainActor () -> NSViewController) ``` ## Parameters `name` Optional display name for the preview, which will appear in the canvas. `traits` Optional list of traits customizing the appearance of the preview. `body` A closure producing an NSViewController. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)