<!--
{
  "availability" : [
    "iOS: 11.0.0 -",
    "iPadOS: 11.0.0 -",
    "macCatalyst: 13.1.0 -",
    "macOS: 10.13.0 -",
    "tvOS: 11.0.0 -",
    "visionOS: 1.0.0 -",
    "watchOS: 4.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "ImageIO",
  "identifier" : "/documentation/ImageIO/CGImageSourceCopyAuxiliaryDataInfoAtIndex(_:_:_:)",
  "metadataVersion" : "0.1.0",
  "role" : "Function",
  "symbol" : {
    "kind" : "Function",
    "modules" : [
      "Image I/O"
    ],
    "preciseIdentifier" : "c:@F@CGImageSourceCopyAuxiliaryDataInfoAtIndex"
  },
  "title" : "CGImageSourceCopyAuxiliaryDataInfoAtIndex(_:_:_:)"
}
-->

# CGImageSourceCopyAuxiliaryDataInfoAtIndex(_:_:_:)

Returns auxiliary data, such as mattes and depth information, that accompany the image.

```
func CGImageSourceCopyAuxiliaryDataInfoAtIndex(_ isrc: CGImageSource, _ index: Int, _ auxiliaryImageDataType: CFString) -> CFDictionary?
```

## Parameters

`isrc`

The image source that contains the image data.

`index`

The zero-based index into the images of the image source. If the index is invalid, this method returns `NULL`.

`auxiliaryImageDataType`

The auxiliary data to retrieve. For a list of possible values, see [Auxiliary Image Data](/documentation/ImageIO/individual-image-properties#Auxiliary-Image-Data) and [Auxiliary Data Types](/documentation/ImageIO/individual-image-properties#Auxiliary-Data-Types).

## Return Value

A dictionary that contains the auxiliary data, or `NULL` if an error occurs.

## Discussion

---

Copyright &copy; 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)