# QLPreviewReplyAttachment
An attachment for a Quick Look preview reply that provides additional content for the system to display a preview.
```
class QLPreviewReplyAttachment
```
## Overview
When providing a data-based Quick Look preview with HTML, use [`QLPreviewReplyAttachment`](/documentation/QuickLookUI/QLPreviewReplyAttachment) to include images, CSS, and other linked content in the HTML of the preview.
Reference content in your html using the `CID` notation for the reference. For instance, if your HTML preview response includes an image, create a [`QLPreviewReplyAttachment`](/documentation/QuickLookUI/QLPreviewReplyAttachment) with the image, add it the reply’s [`attachments`](/documentation/QuickLookUI/QLPreviewReply/attachments) with an associated string, and reference the image with the associated string, prefixed by `cid:`. The following example illustrates returning HTML as a preview reply with an image as an attachment:
```swift
let reply = QLPreviewReply(dataOfContentType: .html,
contentSize: CGSize(width: 750, height: 500)) { htmlReply in
let content = """
Preview
![](\"cid:exampleImage\")
"""
guard let contentData = content.data(using: .utf8) else {
throw PreviewError.previewSetupFailure("Unable to encode preview content")
}
guard let imageFileURL = Bundle.main.url(forResource: "yourImage",
withExtension: "jpg") else {
throw PreviewError.previewSetupFailure("unable to load image")
}
let imageData = try Data(contentsOf: imageFileURL)
htmlReply.attachments["exampleImage"] = QLPreviewReplyAttachment(data: imageData,
contentType: .jpeg)
return contentData
}
reply.title = "HTML Preview Example"
```
## Topics
### Creating a preview reply attachment
[`- initWithData:contentType:`](/documentation/QuickLookUI/QLPreviewReplyAttachment/init(data:contentType:))
Creates a preview reply attachment with the specified type.
### Inspecting a preview reply attachment
[`contentType`](/documentation/QuickLookUI/QLPreviewReplyAttachment/contentType)
The content type of the preview attachment.
[`data`](/documentation/QuickLookUI/QLPreviewReplyAttachment/data)
The data of the preview attachment.
## Relationships
### Conforms To
[`CVarArg`](/documentation/Swift/CVarArg)
[`Hashable`](/documentation/Swift/Hashable)
[`CustomStringConvertible`](/documentation/Swift/CustomStringConvertible)
[`Equatable`](/documentation/Swift/Equatable)
[`NSObjectProtocol`](/documentation/ObjectiveC/NSObjectProtocol)
[`CustomDebugStringConvertible`](/documentation/Swift/CustomDebugStringConvertible)
### Inherits From
[`NSObject-swift.class`](/documentation/ObjectiveC/NSObject-swift.class)
---
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