---
title: kIOMasterPortDefault
framework: iokit
role: symbol
role_heading: Global Variable
path: iokit/kiomasterportdefault
---

# kIOMasterPortDefault

The default mach port used to initiate communication with IOKit.

## Declaration

```swift
let kIOMasterPortDefault: mach_port_t
```

## Discussion

Discussion When specifying a primary port to IOKit functions, the NULL argument indicates "use the default". This is a synonym for NULL, if you'd rather use a named constant.