---
title: "CFRunLoopSourceIsValid(_:)"
framework: corefoundation
role: symbol
role_heading: Function
path: "corefoundation/cfrunloopsourceisvalid(_:)"
---

# CFRunLoopSourceIsValid(_:)

Returns a Boolean value that indicates whether a CFRunLoopSource object is valid and able to fire.

## Declaration

```swift
func CFRunLoopSourceIsValid(_ source: CFRunLoopSource!) -> Bool
```

## Parameters

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

## Return Value

Return Value true if source is valid, otherwise false.

## 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)
- [CFRunLoopSourceSignal(_:)](corefoundation/cfrunloopsourcesignal(_:).md)