---
title: kAudioUnitProperty_ClassInfoFromDocument
framework: audiotoolbox
role: symbol
role_heading: Global Variable
path: audiotoolbox/kaudiounitproperty_classinfofromdocument
---

# kAudioUnitProperty_ClassInfoFromDocument

A read/write CFDictionary object, valid on the audio unit global scope.

## Declaration

```swift
var kAudioUnitProperty_ClassInfoFromDocument: AudioUnitPropertyID { get }
```

## Discussion

Discussion If the audio unit implements this property then it is going to do different actions establishing its state from a document rather than from a user preset. Thus, a host app should use this property first (instead of kAudioUnitProperty_ClassInfo) when restoring the state of an audio unit when opening a document. If the audio unit returns an error (or doesn’t implement this property) then the host should use the same preset with the kAudioUnitProperty_ClassInfo.

## See Also

### Properties

- [kAudioUnitProperty_ElementCount](audiotoolbox/kaudiounitproperty_elementcount.md)
- [kAudioUnitProperty_SupportedNumChannels](audiotoolbox/kaudiounitproperty_supportednumchannels.md)
- [kAudioUnitProperty_AudioChannelLayout](audiotoolbox/kaudiounitproperty_audiochannellayout.md)
- [kAudioUnitProperty_AudioUnitMIDIProtocol](audiotoolbox/kaudiounitproperty_audiounitmidiprotocol.md)
- [kAudioUnitProperty_AUHostIdentifier](audiotoolbox/kaudiounitproperty_auhostidentifier.md)
- [kAudioUnitProperty_BypassEffect](audiotoolbox/kaudiounitproperty_bypasseffect.md)
- [kAudioUnitProperty_ClassInfo](audiotoolbox/kaudiounitproperty_classinfo.md)
- [kAudioUnitProperty_CocoaUI](audiotoolbox/kaudiounitproperty_cocoaui.md)
- [kAudioUnitProperty_ContextName](audiotoolbox/kaudiounitproperty_contextname.md)
- [kAudioUnitProperty_CPULoad](audiotoolbox/kaudiounitproperty_cpuload.md)
- [kAudioUnitProperty_DependentParameters](audiotoolbox/kaudiounitproperty_dependentparameters.md)
- [kAudioUnitProperty_ElementName](audiotoolbox/kaudiounitproperty_elementname.md)
- [kAudioUnitProperty_FactoryPresets](audiotoolbox/kaudiounitproperty_factorypresets.md)
- [kAudioUnitProperty_FastDispatch](audiotoolbox/kaudiounitproperty_fastdispatch.md)
- [kAudioUnitProperty_FrequencyResponse](audiotoolbox/kaudiounitproperty_frequencyresponse.md)