# protocol_copyProtocolList(_:_:) Returns an array of the protocols adopted by a protocol. ``` func protocol_copyProtocolList(_ proto: Protocol, _ outCount: UnsafeMutablePointer?) -> AutoreleasingUnsafeMutablePointer? ``` ## Parameters `proto` A protocol. `outCount` Upon return, contains the number of elements in the returned array. ## Return Value A C array of protocols adopted by `proto`. The array contains `*outCount` pointers followed by a `NULL` terminator. You must free the array with `free()`. ## Discussion If the protocol declares no properties, `NULL` is returned and `*outCount` is `0`. --- 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)