---
title: VNTrackingRequest
framework: vision
role: symbol
role_heading: Class
path: vision/vntrackingrequest
---

# VNTrackingRequest

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

## Declaration

```swift
class VNTrackingRequest
```

## Overview

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, and provide observations you’d like to track by setting the inputObservation initial bounding box.

## Topics

### Configuring a Tracking Request

- [VNRequestTrackingLevel](vision/vnrequesttrackinglevel.md)
- [inputObservation](vision/vntrackingrequest/inputobservation.md)
- [trackingLevel](vision/vntrackingrequest/trackinglevel.md)
- [isLastFrame](vision/vntrackingrequest/islastframe.md)

### Getting the Number of Trackers

- [supportedNumber(ofTrackersAndReturnError:)](vision/vntrackingrequest/supportednumber(oftrackersandreturnerror:).md)

## Relationships

### Inherits From

- [VNImageBasedRequest](vision/vnimagebasedrequest.md)

### Inherited By

- [VNTrackObjectRequest](vision/vntrackobjectrequest.md)
- [VNTrackRectangleRequest](vision/vntrackrectanglerequest.md)

### Conforms To

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

## See Also

### Object tracking

- [Tracking the User’s Face in Real Time](vision/tracking-the-user-s-face-in-real-time.md)
- [Tracking Multiple Objects or Rectangles in Video](vision/tracking-multiple-objects-or-rectangles-in-video.md)
- [VNTrackRectangleRequest](vision/vntrackrectanglerequest.md)
- [VNTrackObjectRequest](vision/vntrackobjectrequest.md)
- [VNDetectedObjectObservation](vision/vndetectedobjectobservation.md)