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# cancel()

Changes the cancelled state of the receiver to indicate that it should exit.

```
func cancel()
```

## Discussion

The semantics of this method are the same as those used for [`Operation`](/documentation/Foundation/Operation). This method sets state information in the receiver that is then reflected by the [`isCancelled`](/documentation/Foundation/Thread/isCancelled) property. Threads that support cancellation should periodically call the [`isCancelled`](/documentation/Foundation/Thread/isCancelled) method to determine if the thread has in fact been cancelled, and exit if it has been.

For more information about cancellation and operation objects, see [`Operation`](/documentation/Foundation/Operation).

## See Also

[`isCancelled`](/documentation/Foundation/Thread/isCancelled)

A Boolean value that indicates whether the receiver is cancelled.


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