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# startCapture(handler:completionHandler:)

Starts screen and audio capture.

```
func startCapture(handler captureHandler: ((CMSampleBuffer, RPSampleBufferType, (any Error)?) -> Void)?, completionHandler: (@Sendable ((any Error)?) -> Void)? = nil)
```

## Parameters

`captureHandler`

A block that is called continuously during screen capture.

- sampleBuffer: A <doc://com.apple.documentation/documentation/CoreMedia/cmsamplebuffer-api> object containing either audio or video data.
- bufferType: An [`RPSampleBufferType`](/documentation/ReplayKit/RPSampleBufferType) identifying the media type of the recorded sample.
- error: Contains an error code if screen capture failed to start. Otherwise, the value of this parameter is `nil`.

`completionHandler`

A block that is called when screen capture has started.

- error: If an error occurred, this parameter holds an object that explains the error. Otherwise, the value of this parameter is `nil`. See [`RPRecordingErrorCode`](/documentation/ReplayKit/RPRecordingErrorCode) for a list of error codes to ReplayKit.

## Discussion

> Important:
> You can call this method from synchronous code using a completion handler, as shown on this page, or you can call it as an asynchronous method that has the following declaration:
> 
> ```swift
> func startCapture(handler captureHandler: ((CMSampleBuffer, RPSampleBufferType, Error?) -> Void)?) async throws
> ```
> 
> For information about concurrency and asynchronous code in Swift, see <doc://com.apple.documentation/documentation/Swift/calling-objective-c-apis-asynchronously>.

---

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