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

# startWriting()

Tells the writer to start writing its output.

## Declaration

```swift
func startWriting() -> Bool
```

## Return Value

Return Value true if writing starts successfully; otherwise false.

## Discussion

Discussion You must call this method after you configure the writer and add its inputs to prepare the object to write data. After you call this method, your app can start writing sessions by calling startSession(atSourceTime:) and can write media samples using the methods that the asset writer’s inputs provide. If writing fails to start, this method returns false. In this case, check the values of the status and error properties to determine the reason for the failure.

## See Also

### Managing writing sessions

- [start()](avfoundation/avassetwriter/start().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)