# createReferenceObject(transform:center:extent:completionHandler:) Creates a reference object (for 3D object detection) from the specified region of the session’s world space. ``` func createReferenceObject(transform: simd_float4x4, center: simd_float3, extent: simd_float3, completionHandler: @escaping @Sendable (ARReferenceObject?, (any Error)?) -> Void) ``` ## Parameters `transform` A transform matrix defining the origin and orientation of the local coordinate system for the region to extract. `center` A point, relative to the origin specified by `transform`, that defines the center of the bounding box for the region to extract. `extent` The width, height, and depth of the region to extract, centered on the `center` point and oriented to the local coordinate system specified by `transform`. `completionHandler` A handler to be invoked asynchronously after ARKit finishes creating the reference object. The handler takes two parameters: - referenceObject: A [`ARReferenceObject`](/documentation/ARKit/ARReferenceObject) that represents the specified region of the world map, or `nil` if a reference object could not be created. - error: If the `referenceObject` is `nil`, an [`ARError`](/documentation/ARKit/ARError) describing the failure. ## Discussion > Important: This method is valid only when running a session with ``doc://com.apple.arkit/documentation/ARKit/ARObjectScanningConfiguration``, which enables the high-fidelity spatial data collection needed for scanning reference objects. Calling this method on a session with a different configuration immediately invokes your `completionHandler` with an error. To use the extracted reference object for 3D object detection, assign it to the [`detectionObjects`](/documentation/ARKit/ARWorldTrackingConfiguration/detectionObjects) property of a world tracking configuration. You can bundle reference objects in an app by saving them to files and adding them to an Xcode asset catalog. When ARKit detects a reference image, the transform of the resulting [`ARObjectAnchor`](/documentation/ARKit/ARObjectAnchor) is based on the orgin of the reference object’s coordinate system—the transform you specify when extracting the reference object. For example, if a reference object represents a physical item that sits on a horizontal surface, virtual content should appear to sit on whatever surface the physical object does. To adjust a reference object’s origin after extracting it, use the [`applyingTransform(_:)`](/documentation/ARKit/ARReferenceObject/applyingTransform(_:)) method. --- 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)