# CFPropertyListWriteToStream(_:_:_:_:) Writes the bytes of a property list serialization out to a stream. ``` func CFPropertyListWriteToStream(_ propertyList: CFPropertyList!, _ stream: CFWriteStream!, _ format: CFPropertyListFormat, _ errorString: UnsafeMutablePointer?>!) -> CFIndex ``` ## Parameters `propertyList` The property list to write out. `stream` The stream to write to. The stream must be opened and configured—this function simply writes bytes to the stream. `format` A constant that specifies the format used to write `propertyList`. See [`CFPropertyListFormat`](/documentation/CoreFoundation/CFPropertyListFormat) for possible values. `errorString` On return, `NULL` if the conversion is successful, otherwise a string that describes the nature of the errors. Error messages are not localized, but may be in the future, so they are not currently suitable for comparison. Pass `NULL` if you do not wish to receive an error string. 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) . ## Return Value The number of bytes written, or `0` if an error occurred. If `0` is returned, `errorString` will contain an error message. ## Discussion This function leaves the stream open after reading the content. When reading a property list, this function expects the reading stream to end wherever the writing ended, so that the end of the property list data can be identified. ### Special Considerations > Warning: > This function is obsolete and will be deprecated soon. Use ``doc://com.apple.corefoundation/documentation/CoreFoundation/CFPropertyListWrite(_:_:_:_:_:)`` instead. --- 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)