<!--
{
  "availability" : [
    "iOS: 11.0.0 -",
    "iPadOS: 11.0.0 -",
    "macCatalyst: 13.1.0 -",
    "macOS: 10.13.0 -",
    "tvOS: 11.0.0 -",
    "visionOS: 1.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "Vision",
  "identifier" : "/documentation/Vision/VNTrackingRequest",
  "metadataVersion" : "0.1.0",
  "role" : "Class",
  "symbol" : {
    "kind" : "Class",
    "modules" : [
      "Vision"
    ],
    "preciseIdentifier" : "c:objc(cs)VNTrackingRequest"
  },
  "title" : "VNTrackingRequest"
}
-->

# VNTrackingRequest

The abstract superclass for image-analysis requests that track unique features across multiple images or video frames.

```
class VNTrackingRequest
```

## Overview

Instantiate a tracking request subclass to perform object tracking across multiple frames of an image. After initialization, configure the degree of accuracy by setting [`trackingLevel`](/documentation/Vision/VNTrackingRequest/trackingLevel), and provide observations you’d like to track by setting the [`inputObservation`](/documentation/Vision/VNTrackingRequest/inputObservation) initial bounding box.

## Topics

### Configuring a Tracking Request

[`VNRequestTrackingLevel`](/documentation/Vision/VNRequestTrackingLevel)

An enumeration of tracking priorities.

[`inputObservation`](/documentation/Vision/VNTrackingRequest/inputObservation)

The observation object defining a region to track.

[`trackingLevel`](/documentation/Vision/VNTrackingRequest/trackingLevel)

A value for specifying whether to prioritize speed or location accuracy.

[`isLastFrame`](/documentation/Vision/VNTrackingRequest/isLastFrame)

A Boolean that indicates the last frame in a tracking sequence.

### Getting the Number of Trackers

[`supportedNumber(ofTrackersAndReturnError:)`](/documentation/Vision/VNTrackingRequest/supportedNumber(ofTrackersAndReturnError:))

Returns the maximum number of simultaneous trackers for the request.


---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)