---
title: start()
framework: avfaudio
role: symbol
role_heading: Instance Method
path: avfaudio/avaudioengine/start()
---

# start()

Starts the audio engine.

## Declaration

```swift
func start() throws
```

## Discussion

Discussion This method calls the prepare() method if you don’t call it after invoking stop(). It then starts the audio hardware through the AVAudioInputNode and AVAudioOutputNode instances in the audio engine. This method throws an error when: There’s a problem in the structure of the graph, such as the input can’t route to an output or to a recording tap through converter nodes. An AVAudioSession error occurs. The driver fails to start the hardware.

## See Also

### Playing Audio

- [prepare()](avfaudio/avaudioengine/prepare().md)
- [isRunning](avfaudio/avaudioengine/isrunning.md)
- [pause()](avfaudio/avaudioengine/pause().md)
- [stop()](avfaudio/avaudioengine/stop().md)
- [reset()](avfaudio/avaudioengine/reset().md)
- [withMusicSequence(_:)](avfaudio/avaudioengine/withmusicsequence(_:).md)