# Audio Session Categories Category identifiers for audio sessions, used as values for the [`kAudioSessionProperty_AudioCategory`](/documentation/AudioToolbox/kAudioSessionProperty_AudioCategory) property. ## Discussion Each app running in iOS has a single audio session, which in turn has a single category. You can change your audio session’s category while your app is running. You can refine the configuration provided by the [`kAudioSessionCategory_RecordAudio`](/documentation/AudioToolbox/kAudioSessionCategory_RecordAudio) and [`kAudioSessionCategory_PlayAndRecord`](/documentation/AudioToolbox/kAudioSessionCategory_PlayAndRecord) categories by using an audio session mode, as described in [Audio Session Modes](/documentation/AudioToolbox/1618405-audio-session-modes). Use the [`kAudioSessionCategory_AmbientSound`](/documentation/AudioToolbox/kAudioSessionCategory_AmbientSound) category when you want your sounds to mix with other audio (such as from the iPod app). Use one of the other playback categories when you want audio from other apps to be silenced when your session is active. However, you can enable mixing for the [`kAudioSessionCategory_MediaPlayback`](/documentation/AudioToolbox/kAudioSessionCategory_MediaPlayback) and [`kAudioSessionCategory_PlayAndRecord`](/documentation/AudioToolbox/kAudioSessionCategory_PlayAndRecord) categories by using the [`kAudioSessionProperty_OverrideCategoryMixWithOthers`](/documentation/AudioToolbox/kAudioSessionProperty_OverrideCategoryMixWithOthers) property. For more information on audio session categories, see [Audio Session Programming Guide](https://developer.apple.com/library/archive/documentation/Audio/Conceptual/AudioSessionProgrammingGuide/Introduction/Introduction.html#//apple_ref/doc/uid/TP40007875). ## Topics ### Constants [`var kAudioSessionCategory_AmbientSound: Int`](/documentation/AudioToolbox/kAudioSessionCategory_AmbientSound) For an app in which sound playback is nonprimary—that is, your app can be used successfully with the sound turned off. [`var kAudioSessionCategory_SoloAmbientSound: Int`](/documentation/AudioToolbox/kAudioSessionCategory_SoloAmbientSound) The default category, used unless you set a category with the [`AudioSessionSetProperty(_:_:_:)`](/documentation/AudioToolbox/AudioSessionSetProperty(_:_:_:)) function. [`var kAudioSessionCategory_MediaPlayback: Int`](/documentation/AudioToolbox/kAudioSessionCategory_MediaPlayback) For playing recorded music or other sounds that are central to the successful use of your app. [`var kAudioSessionCategory_RecordAudio: Int`](/documentation/AudioToolbox/kAudioSessionCategory_RecordAudio) For recording audio; this category silences playback audio. Recording continues with the screen locked. [`var kAudioSessionCategory_PlayAndRecord: Int`](/documentation/AudioToolbox/kAudioSessionCategory_PlayAndRecord) Allows recording (input) and playback (output) of audio, such as for a VOIP (voice over IP) app. [`var kAudioSessionCategory_AudioProcessing: Int`](/documentation/AudioToolbox/kAudioSessionCategory_AudioProcessing) For using an audio hardware codec or signal processor while not playing or recording audio. Use this category, for example, when performing offline audio format conversion. --- Copyright © 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)