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# addOperation(_:)

Adds the specified operation to the receiver.

```
func addOperation(_ op: Operation)
```

## Parameters

`op`

The operation to be added to the queue.

## Discussion

Once added, the specified operation remains in the queue until it finishes executing.

> Important:
> An operation object can be in at most one operation queue at a time and this method throws an ``doc://com.apple.foundation/documentation/Foundation/NSExceptionName/invalidArgumentException`` exception if the operation is already in another queue. Similarly, this method throws an ``doc://com.apple.foundation/documentation/Foundation/NSExceptionName/invalidArgumentException`` exception if the operation is currently executing or has already finished executing.

## See Also

[`cancel()`](/documentation/Foundation/Operation/cancel())

Advises the operation object that it should stop executing its task.

[`isExecuting`](/documentation/Foundation/Operation/isExecuting)

A Boolean value indicating whether the operation is currently executing.


---

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