---
title: "CFRunLoopIsWaiting(_:)"
framework: corefoundation
role: symbol
role_heading: Function
path: "corefoundation/cfrunloopiswaiting(_:)"
---

# CFRunLoopIsWaiting(_:)

Returns a Boolean value that indicates whether the run loop is waiting for an event.

## Declaration

```swift
func CFRunLoopIsWaiting(_ rl: CFRunLoop!) -> Bool
```

## Parameters

- `rl`: The run loop to examine.

## Return Value

Return Value true if rl has no events to process and is blocking, waiting for a source or timer to become ready to fire; false if rl either is not running or is currently processing a source, timer, or observer.

## Discussion

Discussion This function is useful only to test the state of another thread’s run loop. When called with the current thread’s run loop, this function always returns false.

## See Also

### Starting and Stopping a Run Loop

- [CFRunLoopRun()](corefoundation/cfrunlooprun().md)
- [CFRunLoopRunInMode(_:_:_:)](corefoundation/cfrunloopruninmode(_:_:_:).md)
- [CFRunLoopWakeUp(_:)](corefoundation/cfrunloopwakeup(_:).md)
- [CFRunLoopStop(_:)](corefoundation/cfrunloopstop(_:).md)