# PreviewTrait Customizations that you can apply to a preview. ``` @MainActor struct PreviewTrait ``` ## Topics ### Getting a layout [`defaultLayout`](/documentation/DeveloperToolsSupport/PreviewTrait/defaultLayout) Center the preview in a container the size of the device on which the preview is running. [`fixedLayout(width:height:)`](/documentation/DeveloperToolsSupport/PreviewTrait/fixedLayout(width:height:)) Center the preview in a fixed size container with the given dimensions. [`fixedLayout(width:height:depth:)`](/documentation/DeveloperToolsSupport/PreviewTrait/fixedLayout(width:height:depth:)) Centers the preview in a fixed-size, 3D container. [`sizeThatFitsLayout`](/documentation/DeveloperToolsSupport/PreviewTrait/sizeThatFitsLayout) Fit the container to the size of the preview when offered the size of the device that the preview is running on. ### Getting an orientation [`portrait`](/documentation/DeveloperToolsSupport/PreviewTrait/portrait) The device is in portrait mode, with the top of the device on top. [`portraitUpsideDown`](/documentation/DeveloperToolsSupport/PreviewTrait/portraitUpsideDown) The device is in portrait mode, but is upside down. [`landscapeLeft`](/documentation/DeveloperToolsSupport/PreviewTrait/landscapeLeft) The device is in landscape mode, with the top of the device on the left. [`landscapeRight`](/documentation/DeveloperToolsSupport/PreviewTrait/landscapeRight) The device is in landscape mode, with the top of the device on the right. --- 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)