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# CFRunLoopContainsSource(_:_:_:)

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

```
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 [`commonModes`](/documentation/CoreFoundation/CFRunLoopMode/commonModes) to search for `source` in the set of objects monitored by all the common modes.

## Return Value

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

## Discussion

If `source` was added to [`commonModes`](/documentation/CoreFoundation/CFRunLoopMode/commonModes), this function returns `true` if `mode` is either [`commonModes`](/documentation/CoreFoundation/CFRunLoopMode/commonModes) or any of the modes that has been added to the set of common modes.

---

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