---
title: signal()
framework: foundation
role: symbol
role_heading: Instance Method
path: foundation/nscondition/signal()
---

# signal()

Signals the condition, waking up one thread waiting on it.

## Declaration

```swift
func signal()
```

## Discussion

Discussion You use this method to wake up one thread that is waiting on the condition. You may call this method multiple times to wake up multiple threads. If no threads are waiting on the condition, this method does nothing. To avoid race conditions, you should invoke this method only while the receiver is locked.

## See Also

### Signaling Waiting Threads

- [broadcast()](foundation/nscondition/broadcast().md)