---
title: "CFRunLoopSourceSignal(_:)"
framework: corefoundation
role: symbol
role_heading: Function
path: "corefoundation/cfrunloopsourcesignal(_:)"
---

# CFRunLoopSourceSignal(_:)

Signals a CFRunLoopSource object, marking it as ready to fire.

## Declaration

```swift
func CFRunLoopSourceSignal(_ source: CFRunLoopSource!)
```

## Parameters

- `source`: The run loop source to signal.

## Discussion

Discussion This function has no effect on version 1 sources, which are automatically handled when Mach messages arrive for them. After signaling a version 0 source, you need to call CFRunLoopWakeUp(_:) on one of the run loops in which the source is registered to get the source handled immediately.

## See Also

### CFRunLoopSource Miscellaneous Functions

- [CFRunLoopSourceCreate(_:_:_:)](corefoundation/cfrunloopsourcecreate(_:_:_:).md)
- [CFRunLoopSourceGetContext(_:_:)](corefoundation/cfrunloopsourcegetcontext(_:_:).md)
- [CFRunLoopSourceGetOrder(_:)](corefoundation/cfrunloopsourcegetorder(_:).md)
- [CFRunLoopSourceGetTypeID()](corefoundation/cfrunloopsourcegettypeid().md)
- [CFRunLoopSourceInvalidate(_:)](corefoundation/cfrunloopsourceinvalidate(_:).md)
- [CFRunLoopSourceIsValid(_:)](corefoundation/cfrunloopsourceisvalid(_:).md)