---
title: start()
framework: avfoundation
role: symbol
role_heading: Instance Method
path: avfoundation/avassetwriter/start()
---

# start()

Prepares the writer to write media data to its output file.

## Declaration

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

## Discussion

Discussion note: An error if reading fails to start.

## See Also

### Managing writing sessions

- [startWriting()](avfoundation/avassetwriter/startwriting().md)
- [startSession(atSourceTime:)](avfoundation/avassetwriter/startsession(atsourcetime:).md)
- [endSession(atSourceTime:)](avfoundation/avassetwriter/endsession(atsourcetime:).md)
- [finishWriting(completionHandler:)](avfoundation/avassetwriter/finishwriting(completionhandler:).md)
- [cancelWriting()](avfoundation/avassetwriter/cancelwriting().md)
- [finishWriting()](avfoundation/avassetwriter/finishwriting().md)