# outputCaptionProvider(for:validationDelegate:) Attaches the output to the reader and returns an output provider for reading caption groups. ``` func outputCaptionProvider(for output: AVAssetReaderTrackOutput, validationDelegate: (any AVAssetReaderCaptionValidationHandling)? = nil) -> sending AVAssetReaderOutput.Provider ``` ## Parameters `output` The output to be attached to the reader. ## Return Value A reader output provider with an interface for reading caption groups. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)