---
title: "CGImageSourceCopyAuxiliaryDataInfoAtIndex(_:_:_:)"
framework: imageio
role: symbol
role_heading: Function
path: "imageio/cgimagesourcecopyauxiliarydatainfoatindex(_:_:_:)"
---

# CGImageSourceCopyAuxiliaryDataInfoAtIndex(_:_:_:)

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

## Declaration

```swift
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 doc://com.apple.imageio/documentation/ImageIO/individual-image-properties#Auxiliary-Image-Data and doc://com.apple.imageio/documentation/ImageIO/individual-image-properties#Auxiliary-Data-Types.

## Return Value

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

## See Also

### Getting Information From an Image Source

- [CGImageSourceGetTypeID()](imageio/cgimagesourcegettypeid().md)
- [CGImageSourceGetType(_:)](imageio/cgimagesourcegettype(_:).md)
- [CGImageSourceCopyTypeIdentifiers()](imageio/cgimagesourcecopytypeidentifiers().md)
- [CGImageSourceGetCount(_:)](imageio/cgimagesourcegetcount(_:).md)
- [CGImageSourceCopyProperties(_:_:)](imageio/cgimagesourcecopyproperties(_:_:).md)
- [CGImageSourceCopyPropertiesAtIndex(_:_:_:)](imageio/cgimagesourcecopypropertiesatindex(_:_:_:).md)