---
title: "CFRunLoopContainsSource(_:_:_:)"
framework: corefoundation
role: symbol
role_heading: Function
path: "corefoundation/cfrunloopcontainssource(_:_:_:)"
---

# CFRunLoopContainsSource(_:_:_:)

Returns a Boolean value that indicates whether a run loop mode contains a particular CFRunLoopSource object.

## Declaration

```swift
func CFRunLoopContainsSource(_ rl: CFRunLoop!, _ source: CFRunLoopSource!, _ mode: CFRunLoopMode!) -> Bool
```

## Parameters

- `rl`: The run loop to examine.
- `source`: The run loop source for which to search.
- `mode`: The run loop mode of rl in which to search. Use the constant doc://com.apple.corefoundation/documentation/CoreFoundation/CFRunLoopMode/commonModes to search for source in the set of objects monitored by all the common modes.

## Return Value

Return Value true if source is in mode mode of the run loop rl, otherwise false.

## Discussion

Discussion If source was added to commonModes, this function returns true if mode is either commonModes or any of the modes that has been added to the set of common modes.

## See Also

### Managing Sources

- [CFRunLoopAddSource(_:_:_:)](corefoundation/cfrunloopaddsource(_:_:_:).md)
- [CFRunLoopRemoveSource(_:_:_:)](corefoundation/cfrunloopremovesource(_:_:_:).md)