---
title: kAudioSessionNoCategorySet
framework: audiotoolbox
role: symbol
role_heading: Global Variable
path: audiotoolbox/kaudiosessionnocategoryset
---

# kAudioSessionNoCategorySet

The audio operation failed because it requires the audio session to have an explicitly-set category, but none was set. To use a hardware codec you must explicitly initialize the audio session and explicitly set an audio session category.

## Declaration

```swift
var kAudioSessionNoCategorySet: Int { get }
```

## See Also

### Constants

- [kAudioSessionNoError](audiotoolbox/kaudiosessionnoerror.md)
- [kAudioSessionNotInitialized](audiotoolbox/kaudiosessionnotinitialized.md)
- [kAudioSessionAlreadyInitialized](audiotoolbox/kaudiosessionalreadyinitialized.md)
- [kAudioSessionInitializationError](audiotoolbox/kaudiosessioninitializationerror.md)
- [kAudioSessionUnsupportedPropertyError](audiotoolbox/kaudiosessionunsupportedpropertyerror.md)
- [kAudioSessionBadPropertySizeError](audiotoolbox/kaudiosessionbadpropertysizeerror.md)
- [kAudioSessionNotActiveError](audiotoolbox/kaudiosessionnotactiveerror.md)
- [kAudioServicesNoHardwareError](audiotoolbox/kaudioservicesnohardwareerror.md)
- [kAudioSessionIncompatibleCategory](audiotoolbox/kaudiosessionincompatiblecategory.md)
- [kAudioSessionUnspecifiedError](audiotoolbox/kaudiosessionunspecifiederror.md)