---
title: "QLThumbnailRequestSetImageWithData(_:_:_:)"
framework: quicklook
role: symbol
role_heading: Function
path: "quicklook/qlthumbnailrequestsetimagewithdata(_:_:_:)"
---

# QLThumbnailRequestSetImageWithData(_:_:_:)

Sets the response to the thumbnail request to image data saved within the document.

## Declaration

```swift
func QLThumbnailRequestSetImageWithData(_ thumbnail: QLThumbnailRequest!, _ data: CFData!, _ properties: CFDictionary!)
```

## Parameters

- `thumbnail`: The thumbnail request object.
- `data`: The image data, which must be in a format supported by the Image I/O framework (JPG, PNG, and so on). In other words, a content type of kUTTypeImage is assumed. (ImageIO.framework is a subframework of the umbrella Application Services framework.)
- `properties`: A dictionary of properties. The only property that you can currently specify is kCGImageSourceTypeIdentifierHint; see https://developer.apple.com/library/archive/documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/Introduction/Introduction.html#//apple_ref/doc/uid/TP30001066 for information about this property.

## Discussion

Discussion This function returns the thumbnail as a CFData object containing image data. The document’s application must save this data as part of the document’s data; the generator retrieves it and uses this function to return it to the client. Before you call this function, call QLThumbnailRequestGetMaximumSize(_:) to obtain the maximum allowed size for the thumbnail and resize the image if necessary. Special Considerations Thread-safety: This function should be called in the same thread as the thumbnail request is made in; generally, this is the same thread in which the GenerateThumbnailForURL callback was invoked.

## See Also

### Handling thumbnail requests

- [QLThumbnailRequestCopyContentUTI(_:)](quicklook/qlthumbnailrequestcopycontentuti(_:).md)
- [QLThumbnailRequestCopyOptions(_:)](quicklook/qlthumbnailrequestcopyoptions(_:).md)
- [QLThumbnailRequestCopyURL(_:)](quicklook/qlthumbnailrequestcopyurl(_:).md)
- [QLThumbnailRequestCreateContext(_:_:_:_:)](quicklook/qlthumbnailrequestcreatecontext(_:_:_:_:).md)
- [QLThumbnailRequestFlushContext(_:_:)](quicklook/qlthumbnailrequestflushcontext(_:_:).md)
- [QLThumbnailRequestGetDocumentObject(_:)](quicklook/qlthumbnailrequestgetdocumentobject(_:).md)
- [QLThumbnailRequestGetGeneratorBundle(_:)](quicklook/qlthumbnailrequestgetgeneratorbundle(_:).md)
- [QLThumbnailRequestGetMaximumSize(_:)](quicklook/qlthumbnailrequestgetmaximumsize(_:).md)
- [QLThumbnailRequestGetTypeID()](quicklook/qlthumbnailrequestgettypeid().md)
- [QLThumbnailRequestIsCancelled(_:)](quicklook/qlthumbnailrequestiscancelled(_:).md)
- [QLThumbnailRequestSetDocumentObject(_:_:_:)](quicklook/qlthumbnailrequestsetdocumentobject(_:_:_:).md)
- [QLThumbnailRequestSetImage(_:_:_:)](quicklook/qlthumbnailrequestsetimage(_:_:_:).md)
- [QLThumbnailRequestSetImageAtURL(_:_:_:)](quicklook/qlthumbnailrequestsetimageaturl(_:_:_:).md)
- [QLThumbnailRequestSetThumbnailWithDataRepresentation(_:_:_:_:_:)](quicklook/qlthumbnailrequestsetthumbnailwithdatarepresentation(_:_:_:_:_:).md)
- [QLThumbnailRequestSetThumbnailWithURLRepresentation(_:_:_:_:_:)](quicklook/qlthumbnailrequestsetthumbnailwithurlrepresentation(_:_:_:_:_:).md)