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# VNRequestProgressProviding

A protocol for providing progress information on long-running tasks in Vision.

```
protocol VNRequestProgressProviding : NSObjectProtocol
```

## Overview

Adopt this protocol for potentially long-running Vision requests to provide information about progress throughout processing. For example, you can use the optional [`progressHandler`](/documentation/Vision/VNRequestProgressProviding/progressHandler) to update the user interface, provide a percentage of completion, or process partial results.

> Note:
> The Vision framework may call the progress handler on a different dispatch queue from the thread on which you initiated the original request, so ensure that your handler can execute asynchronously, in a thread-safe manner.

## Topics

### Tracking Progress

[`progressHandler`](/documentation/Vision/VNRequestProgressProviding/progressHandler)

A block of code executed periodically during a Vision request to report progress on long-running tasks.

[`indeterminate`](/documentation/Vision/VNRequestProgressProviding/indeterminate)

A Boolean set to true when a request can’t determine its progress in fractions completed.


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