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# QLThumbnailDispatchAsync(_:_:_:)

Creates a thumbnail in the background on the provided background queue.

```
func QLThumbnailDispatchAsync(_ thumbnail: QLThumbnail!, _ queue: dispatch_queue_t!, _ completion: (() -> Void)!)
```

## Parameters

`thumbnail`

The thumbnail to compute.

`queue`

The queue that’s used to create the thumbnail.

`completion`

The completion block that’s called when the thumbnail is created. The completion block is always called, even if the thumbnail computation is canceled.

---

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