---
title: "validateCaptionConversion(warningHandler:)"
framework: avfoundation
role: symbol
role_heading: Instance Method
path: "avfoundation/avcaptionconversionvalidator/validatecaptionconversion(warninghandler:)"
---

# validateCaptionConversion(warningHandler:)

Validates the object’s captions.

## Declaration

```swift
func validateCaptionConversion(warningHandler handler: @escaping @Sendable (AVCaptionConversionWarning?) -> Void)
```

## Parameters

- `handler`: The callback the system invokes when it finishes validation.

## Discussion

Discussion When the object finishes validating and reports all warnings, it invokes the callback once with a value of nil for its warning parameter. When this occurs, the validator’s status value changes to AVCaptionConversionValidator.Status.completed. Stop an in-progress validation operation by calling stopValidating(). important: It’s only valid to call this method when the validator’s state is AVCaptionConversionValidator.Status.unknown.

## See Also

### Validating captions

- [warnings](avfoundation/avcaptionconversionvalidator/warnings.md)
- [AVCaptionConversionWarning](avfoundation/avcaptionconversionwarning.md)
- [stopValidating()](avfoundation/avcaptionconversionvalidator/stopvalidating().md)