# SCNSceneSourceStatusHandler The signature for the block that SceneKit calls periodically to report progress while loading a scene. ``` typealias SCNSceneSourceStatusHandler = (Float, SCNSceneSourceStatus, (any Error)?, UnsafeMutablePointer) -> Void ``` ## Discussion You provide a block with this signature when using the [`scene(options:statusHandler:)`](/documentation/SceneKit/SCNSceneSource/scene(options:statusHandler:)) method. The block takes four parameters: - totalProgress: A floating-point number between `0.0` and `1.0` indicating the overall progress of loading the scene. A value of `0.0` indicates that the loading process has just begun, and a value of `1.0` indicates that the process has completed. - status: A constant identifying one of the distinct phases of SceneKit’s loading procedure. See [`SCNSceneSourceStatus`](/documentation/SceneKit/SCNSceneSourceStatus) for possible values. - error: An error object describing any error that has occurred during scene loading, or `nil` if no errors has been encountered. - stopLoading: A reference to a Boolean value. Set `*stop` to within the block to abort further processing of the scene source’s contents. --- 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)