# nw_framer_create_definition(_:_:_:) Initializes a new protocol definition based on your protocol implementation. ``` func nw_framer_create_definition(_ identifier: UnsafePointer, _ flags: UInt32, _ start_handler: @escaping nw_framer_start_handler_t) -> nw_protocol_definition_t ``` ## Discussion Each time you initialize a protocol definition with your custom start handler, a new definition is created that will not be considered equal to other definitions. If you need to associate messages with a protocol you have added to a connection’s protocol stack, make sure to use the same definition. --- 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)