A CFMachPort object is a wrapper for a native Mach port (mach_port_t). Mach ports are the native communication channel for the macOS kernel.

CFMachPort does not provide a function to send messages, so you primarily use a CFMachPort object if you need to listen to a Mach port that you obtained by other means. You can get a callback when a message arrives on the port or when the port becomes invalid, such as when the native port dies.

To listen for messages you need to create a run loop source with CFMachPortCreateRunLoopSource and add it to a run loop with CFRunLoopAddSource.

To send data, you must use the Mach APIs with the native Mach port, which is not described here. Alternatively, you can use a CFMessagePort object, which can send arbitrary data.

Mach ports only support communication on the local machine. For network communication, you have to use a CFSocket object.


Creating a CFMachPort Object


Creates a CFMachPort object with a new Mach port.


Creates a CFMachPort object for a pre-existing native Mach port.

Configuring a CFMachPort Object


Invalidates a CFMachPort object, stopping it from receiving any more messages.


Creates a CFRunLoopSource object for a CFMachPort object.


Sets the callback function invoked when a CFMachPort object is invalidated.

Examining a CFMachPort Object


Returns the context information for a CFMachPort object.


Returns the invalidation callback function for a CFMachPort object.


Returns the native Mach port represented by a CFMachPort object.


Returns a Boolean value that indicates whether a CFMachPort object is valid and able to receive messages.

Getting the CFMachPort Type ID


Returns the type identifier for the CFMachPort opaque type.



Callback invoked to process a message received on a CFMachPort object.


Callback invoked when a CFMachPort object is invalidated.

Data Types


A structure that contains program-defined data and callbacks with which you can configure a CFMachPort object’s behavior.


A reference to a CFMachPort object.

See Also

Opaque Types


The CFFileDescriptor provides an opaque type to monitor file descriptors for read and write activity via CFRunLoop.


CFStringTokenizer allows you to tokenize strings into words, sentences or paragraphs in a language-neutral way. It supports languages such as Japanese and Chinese that do not delimit words by spaces, as well as de-compounding German compounds. You can obtain Latin transcription for tokens. It also provides language identification API.