# CFHTTPMessageCopyAllHeaderFields(_:) Gets all header fields from a `CFHTTPMessage` object. ``` func CFHTTPMessageCopyAllHeaderFields(_ message: CFHTTPMessage) -> Unmanaged? ``` ## Parameters `message` The message to examine. ## Return Value A `CFDictionaryRef` object containing keys and values that are `CFStringRef` objects, where the key is the header fieldname and the dictionary value is the header field’s value. Returns `NULL` if the header fields could not be copied. Ownership follows the [The Create Rule](https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/Concepts/Ownership.html#//apple_ref/doc/uid/20001148-103029). ## Discussion HTTP headers are case insensitive. To simplify your code, certain header field names are canonicalized into their standard form. For example, if the server sends a `content-length` header, it is automatically adjusted to be `Content-Length`. The returned dictionary of headers is configured to be case-preserving during the set operation (unless the key already exists with a different case), and case-insensitive when looking up keys. For example, if you set the header `X-foo`, and then later set the header `X-Foo`, the dictionary’s key will be `X-foo`, but the value will taken from the `X-Foo` header. --- 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)