# enqueue() Reserves a place for the input/output command buffer in the input/output command queue without committing the command buffer. ``` func enqueue() ``` ## Discussion The method saves the next position for the command buffer in the input/output command queue. You can call [`enqueue()`](/documentation/Metal/MTLIOCommandBuffer/enqueue()) at any time relative to encoding commands, but you can only enqueue a command buffer once. To submit a command buffer to GPU for execution, call its [`commit()`](/documentation/Metal/MTLIOCommandBuffer/commit()) method. For example, to fill multiple command buffers asynchronously that execute in a specific order: 1. Call each command buffer’s [`enqueue()`](/documentation/Metal/MTLIOCommandBuffer/enqueue()) method in order. 2. Encode commands into each command buffer on its own, separate thread. 3. Call each command buffer’s [`commit()`](/documentation/Metal/MTLIOCommandBuffer/commit()) in any order. --- 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)