# makeRenderPipelineStateBySpecialization(descriptor:pipeline:) Creates a new render pipeline state from another, previously unspecialized, pipeline state. ``` func makeRenderPipelineStateBySpecialization(descriptor: MTL4PipelineDescriptor, pipeline: any MTLRenderPipelineState) throws -> any MTLRenderPipelineState ``` ## Parameters `descriptor` A render pipeline state descriptor or any type: default, tile, or mesh render pipeline descriptor. `pipeline` A render pipeline state containing unspecialized substate. ## Return Value a fully-specialized pipeline state object upon success, otherwise this function throws. ## Discussion Metal specializes the pipeline state with new state values the descriptor provides, observing the following rules: - The compiler only updates properties that were originally specified as *unspecialized*. It doesn’t modify other already-specialized properties - The compiler sets to their default behavior any unspecialized properties that your passed-in descriptor doesn’t specialize Additionally, there are some cases where the Metal can’t specialize a pipeline: - If the original pipeline state object doesn’t have any unspecialized properties - You can’t re-specialize a previously specialized pipeline state object --- 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)