---
title: QLThumbnailGenerator
framework: quicklookthumbnailing
role: symbol
role_heading: Class
path: quicklookthumbnailing/qlthumbnailgenerator
---

# QLThumbnailGenerator

An object that generates thumbnail images based on provided requirements.

## Declaration

```swift
class QLThumbnailGenerator
```

## Mentioned in

Creating Quick Look Thumbnails to Preview Files in Your App Providing Thumbnails of Your Custom File Types

## Topics

### Getting the Generator Instance

- [shared](quicklookthumbnailing/qlthumbnailgenerator/shared.md)

### Generating a Thumbnail

- [generateBestRepresentation(for:completion:)](quicklookthumbnailing/qlthumbnailgenerator/generatebestrepresentation(for:completion:).md)
- [generateRepresentations(for:update:)](quicklookthumbnailing/qlthumbnailgenerator/generaterepresentations(for:update:).md)
- [QLThumbnailGenerator.Request](quicklookthumbnailing/qlthumbnailgenerator/request.md)

### Saving a Thumbnail

- [saveBestRepresentation(for:to:contentType:completion:)](quicklookthumbnailing/qlthumbnailgenerator/savebestrepresentation(for:to:contenttype:completion:).md)

### Canceling

- [cancel(_:)](quicklookthumbnailing/qlthumbnailgenerator/cancel(_:).md)

### Instance Methods

- [saveBestRepresentation(for:to:as:completion:)](quicklookthumbnailing/qlthumbnailgenerator/savebestrepresentation(for:to:as:completion:).md)

## Relationships

### Inherits From

- [NSObject](objectivec/nsobject-swift.class.md)

### Conforms To

- [CVarArg](swift/cvararg.md)
- [CustomDebugStringConvertible](swift/customdebugstringconvertible.md)
- [CustomStringConvertible](swift/customstringconvertible.md)
- [Equatable](swift/equatable.md)
- [Hashable](swift/hashable.md)
- [NSObjectProtocol](objectivec/nsobjectprotocol.md)

## See Also

### Thumbnail Generation

- [Creating Quick Look Thumbnails to Preview Files in Your App](quicklookthumbnailing/creating-quick-look-thumbnails-to-preview-files-in-your-app.md)
- [QLThumbnailRepresentation](quicklookthumbnailing/qlthumbnailrepresentation.md)