---
title: "CFMachPortCreateRunLoopSource(_:_:_:)"
framework: corefoundation
role: symbol
role_heading: Function
path: "corefoundation/cfmachportcreaterunloopsource(_:_:_:)"
---

# CFMachPortCreateRunLoopSource(_:_:_:)

Creates a CFRunLoopSource object for a CFMachPort object.

## Declaration

```swift
func CFMachPortCreateRunLoopSource(_ allocator: CFAllocator!, _ port: CFMachPort!, _ order: CFIndex) -> CFRunLoopSource!
```

## Parameters

- `allocator`: The allocator to use to allocate memory for the new object. Pass NULL or doc://com.apple.corefoundation/documentation/CoreFoundation/kCFAllocatorDefault to use the current default allocator.
- `port`: The Mach port for which to create a CFRunLoopSource object.
- `order`: A priority index indicating the order in which run loop sources are processed. order is currently ignored by CFMachPort run loop sources. Pass 0 for this value.

## Return Value

Return Value The new CFRunLoopSource object for port. Ownership follows the The Create Rule.

## Discussion

Discussion The run loop source is not automatically added to a run loop. To add the source to a run loop, use CFRunLoopAddSource(_:_:_:).

## See Also

### Configuring a CFMachPort Object

- [CFMachPortInvalidate(_:)](corefoundation/cfmachportinvalidate(_:).md)
- [CFMachPortSetInvalidationCallBack(_:_:)](corefoundation/cfmachportsetinvalidationcallback(_:_:).md)