<!--
{
  "availability" : [
    "iOS: 16.0.0 -",
    "iPadOS: 16.0.0 -",
    "macCatalyst: 16.0.0 -",
    "macOS: 13.0.0 -",
    "tvOS: 16.0.0 -",
    "visionOS: 1.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "AVFAudio",
  "identifier" : "/documentation/AVFAudio/AVParameterEvent",
  "metadataVersion" : "0.1.0",
  "role" : "Class",
  "symbol" : {
    "kind" : "Class",
    "modules" : [
      "AVFAudio"
    ],
    "preciseIdentifier" : "c:objc(cs)AVParameterEvent"
  },
  "title" : "AVParameterEvent"
}
-->

# AVParameterEvent

An object that represents a parameter event on a music track’s destination.

```
class AVParameterEvent
```

## Overview

When you configure an audio unit as the destination for an [`AVMusicTrack`](/documentation/AVFAudio/AVMusicTrack) that contains this event, you can schedule and automate parameter changes.

When the track is playing as part of a sequence, the destination audio unit receives set-parameter messages whose values change smoothly along a linear ramp between each event’s beat location.

If you add an event to an empty, non-automation track, the track becomes an automation track.

## Topics

### Creating a Parameter Event

[`init(parameterID:scope:element:value:)`](/documentation/AVFAudio/AVParameterEvent/init(parameterID:scope:element:value:))

Creates an event with a parameter identifier, scope, element, and value for the parameter to set.

### Configuring a Parameter Event

[`parameterID`](/documentation/AVFAudio/AVParameterEvent/parameterID)

The identifier of the parameter.

[`scope`](/documentation/AVFAudio/AVParameterEvent/scope)

The audio unit scope for the parameter.

[`element`](/documentation/AVFAudio/AVParameterEvent/element)

The element index in the scope.

[`value`](/documentation/AVFAudio/AVParameterEvent/value)

The value of the parameter to set.


---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)