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# microphoneInjectionCapabilitiesChangeNotification

A notification the system posts when its capability to inject audio into an input stream changes.

```
class let microphoneInjectionCapabilitiesChangeNotification: NSNotification.Name
```

## Discussion

Query the notification’s `userInfo` dictionary for [`AVAudioSessionMicrophoneInjectionIsAvailableKey`](/documentation/AVFAudio/AVAudioSessionMicrophoneInjectionIsAvailableKey) to determine whether microphone
injection is available.

## Topics

### User-information keys

[`AVAudioSessionMicrophoneInjectionIsAvailableKey`](/documentation/AVFAudio/AVAudioSessionMicrophoneInjectionIsAvailableKey)

A key to retrieve a Boolean value that indicates whether microphone injection is available.


---

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