# handleBinding(ofBufferNamed:frequency:handler:) Registers a block for SceneKit to call at render time for binding a Metal buffer to the shader program. ``` func handleBinding(ofBufferNamed name: String, frequency: SCNBufferFrequency, handler block: @escaping SCNBufferBindingBlock) ``` ## Parameters `name` The name identifying the buffer in Metal shader source code. `frequency` An option specifying whether SceneKit calls the block only once per rendered frame or more frequently (for example, once for each object to be rendered). `block` A block to be run when SceneKit prepares for rendering with the Metal shader. ## Discussion Use this method to associate a block with a Metal shader program to handle setup of a buffer used in that shader. SceneKit calls your block before rendering any objects whose [`program`](/documentation/SceneKit/SCNShadable/program) property is set to this [`SCNProgram`](/documentation/SceneKit/SCNProgram) object. In the block, use the [`writeBytes(_:count:)`](/documentation/SceneKit/SCNBufferStream/writeBytes(_:count:)) method to provide data for the buffer. --- 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)