# init(audioSession:) Creates a haptic engine from an audio session. ``` init(audioSession: AVAudioSession?) throws ``` ## Parameters `audioSession` The shared audio session, if you’re already using one in your app, to sync with the created engine. For example, pass in if you’re using audio from . Pass in `nil` to use default audio behavior. ## Discussion Create your haptic engine with this initializer if you want the audio behavior of your engine to match other audio APIs in your app. For example, if you’re using to manage audio elsewhere in your app, then you want to share the session’s . In this case, the engine mutes and routes audio in accordance with the passed session. Otherwise, if you don’t pass it a session, it won’t behave the same way as elsewhere in app; audio behaves like , without syncing to a specific session. You should pass `nil` when you need the engine only for playing haptics. --- 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)