---
title: "CFRunLoopObserverIsValid(_:)"
framework: corefoundation
role: symbol
role_heading: Function
path: "corefoundation/cfrunloopobserverisvalid(_:)"
---

# CFRunLoopObserverIsValid(_:)

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

## Declaration

```swift
func CFRunLoopObserverIsValid(_ observer: CFRunLoopObserver!) -> Bool
```

## Parameters

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

## Return Value

Return Value true if observer is valid, otherwise false.

## Discussion

Discussion A nonrepeating observer is automatically invalidated after it is called once.

## See Also

### CFRunLoopObserver Miscellaneous Functions

- [CFRunLoopObserverCreateWithHandler(_:_:_:_:_:)](corefoundation/cfrunloopobservercreatewithhandler(_:_:_:_:_:).md)
- [CFRunLoopObserverCreate(_:_:_:_:_:_:)](corefoundation/cfrunloopobservercreate(_:_:_:_:_:_:).md)
- [CFRunLoopObserverDoesRepeat(_:)](corefoundation/cfrunloopobserverdoesrepeat(_:).md)
- [CFRunLoopObserverGetActivities(_:)](corefoundation/cfrunloopobservergetactivities(_:).md)
- [CFRunLoopObserverGetContext(_:_:)](corefoundation/cfrunloopobservergetcontext(_:_:).md)
- [CFRunLoopObserverGetOrder(_:)](corefoundation/cfrunloopobservergetorder(_:).md)
- [CFRunLoopObserverGetTypeID()](corefoundation/cfrunloopobservergettypeid().md)
- [CFRunLoopObserverInvalidate(_:)](corefoundation/cfrunloopobserverinvalidate(_:).md)