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# parameter(withID:scope:element:)

Searches the tree for a specific version 2 audio unit parameter.

```
func parameter(withID paramID: AudioUnitParameterID, scope: AudioUnitScope, element: AudioUnitElement) -> AUParameter?
```

## Parameters

`paramID`

The parameter ID with which to search the tree.

`scope`

The scope with which to search the tree.

`element`

The element with which to search the tree.

## Return Value

The parameter corresponding to the supplied ID, scope, and element. Returns `nil` if the parameter is nonexistent or if it is not associated with a version 2 audio unit.

## Discussion

Version 2 audio units publish parameters identified by a parameter ID, scope, and element. A host that knows that it is dealing with a version 2 audio unit can locate parameters using this method—for example, for the Apple-supplied system audio units.

---

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