---
title: composition
framework: Core Audio
role: symbol
role_heading: Instance Property
platforms: [macOS 15.0+]
path: coreaudio/audiohardwareaggregatedevice/composition
---

# composition

A Dictionary that describes the composition of the aggregate device. The keys for this CFDicitionary are defined in the AudioAggregateDevice Constants section of AudioHardware.h

## Declaration

```swift
var composition: [String : Any] { get throws }
```