<!--
{
  "documentType" : "article",
  "framework" : "Foundation",
  "identifier" : "/documentation/Foundation/nsport-allocwithzone",
  "metadataVersion" : "0.1.0",
  "role" : "article",
  "title" : "allocWithZone:"
}
-->

# allocWithZone:

Returns an instance of the `NSMachPort` class.

## Discussion

For backward compatibility on Mach, [allocWithZone:](/documentation/Foundation/nsport-allocwithzone) returns an instance of the `NSMachPort` class when sent to the `NSPort` class. Otherwise, it returns an instance of a concrete subclass that can be used for messaging between threads or processes on the local machine, or, in the case of `NSSocketPort`, between processes on separate machines.

## See Also

  [Threading Programming Guide](https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/Multithreading/Introduction/Introduction.html#//apple_ref/doc/uid/10000057i)

  [Distributed Objects Programming Topics](https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/DistrObjects/DistrObjects.html#//apple_ref/doc/uid/10000102i)


---

Copyright &copy; 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)