--- title: Previewing content and running simulations framework: Reality Composer Pro role: article role_heading: Article path: realitycomposerpro/realitycomposerpro-essentials-previewcontentrunsimulations --- # Previewing content and running simulations Test and iterate on your scenes directly in Reality Composer Pro, with or without a linked Xcode project. ## Overview Overview Reality Composer Pro lets you preview or simulate content on both real and virtual devices, with or without a linked Xcode project. You can iterate on your scene and build and run your app without leaving the editor. The Preview tab shows a preview of the currently selected entity you are working on. For example, you can preview any Reality Composer Pro entity in a simulated visionOS or Mac environment — this mode is suited for content creators who want to preview how their scenes look in real time. To test a scene with actual interactions, views, cameras, game controllers, and live code on a real or simulated device, you need to link your Xcode project first. See Linking an Xcode project to learn how. Run simulations in the Reality Composer Pro Viewport At the top of the Viewport, next to the Play icon, click Simulate to view a simulation in the Viewport. Preview content on a connected device At the top of the Viewport, next to the Play icon, click Simulate > Preview on Device. Then click Devices and select the device you want to preview on. If you need to connect an Apple Vision Pro, select Download Reality Composer Pro Preview for visionOS, then click Play. Run simulations for Xcode linked projects Once you have successfully linked an Xcode project, you can use Reality Composer Pro’s Simulator to preview your Xcode and Reality Composer Pro project as a compiled application on either a connected physical device or a simulated device. Above the Viewport, click Running Destinations and then select a connected device or a simulated device. note: The first time you do this, it may take some time for the project to compile. Subsequent simulations for the same device compile and run faster. Load scenes in your app’s view You can load a Reality Composer Pro scene the same way you load a .usdz asset from your app bundle. Specify the Reality Composer Pro package bundle instead, in the make closure of a RealityView initializer. Each Reality Composer Pro package defines a global constant that points to its bundle. The system creates the bundle name by appending “Bundle” to the end of the project’s name. Xcode’s default visionOS template names the Reality Composer Pro project RealityKitContent and the global bundle variable realityKitContentBundle. The following code shows how to load the default bundle into a RealityView: RealityView { content in if let scene = try? await Entity(named: "Biplane", in: realityKitContentBundle) { myDataModel.add(scene) content.add(scene) } } update: { content in // ... } note: The code example above saves a reference to the root node. This isn’t required, but with RealityView, you don’t have ready access to the scene content — unlike ARView on iOS and macOS, which exposes scene content through its scene property. Maintain your own reference to the root entity of your scene in your app’s data model. When RealityKit finishes loading the scene, the scene variable contains the root entity of the specified scene. RealityView adds this entity to content and displays it to the user. ## See Also ### Essentials - [Linking an Xcode project](realitycomposerpro/realitycomposerpro-essentials-linkingxcodeproject.md) - [Configuring the project workspace](realitycomposerpro/realitycomposerpro-essentials-configuringprojectworkspace.md) - [Navigating the Reality Composer Pro workspace](realitycomposerpro/realitycomposerpro-essentials-workspaceoverview.md) - [Adding entities and assets to a scene](realitycomposerpro/realitycomposerpro-essentials-addingentitiestoscene.md) - [Working with the Graph Editor](realitycomposerpro/realitycomposerpro-essentials-grapheditoroverview.md) - [Reusing assets with prototypes and instances](realitycomposerpro/realitycomposerpro-essentials-understandingprototypes.md)