---
title: IOAsyncCallback0
framework: iokit
role: symbol
role_heading: Type Alias
path: iokit/ioasynccallback0
---

# IOAsyncCallback0

standard callback function for asynchronous I/O requests with no extra arguments beyond a refcon and result code.

## Declaration

```swift
typealias IOAsyncCallback0 = (UnsafeMutableRawPointer?, IOReturn) -> Void
```

## Parameters

- `refcon`: The refcon passed into the original I/O request
- `result`: The result of the I/O operation

## See Also

### Callbacks

- [IOAsyncCallback](iokit/ioasynccallback.md)
- [IOAsyncCallback1](iokit/ioasynccallback1.md)
- [IOAsyncCallback2](iokit/ioasynccallback2.md)
- [IOServiceInterestCallback](iokit/ioserviceinterestcallback.md)
- [IOServiceMatchingCallback](iokit/ioservicematchingcallback.md)