---
title: "supportedNumber(ofTrackersAndReturnError:)"
framework: vision
role: symbol
role_heading: Instance Method
path: "vision/vntrackingrequest/supportednumber(oftrackersandreturnerror:)"
---

# supportedNumber(ofTrackersAndReturnError:)

Returns the maximum number of simultaneous trackers for the request.

## Declaration

```swift
func supportedNumber(ofTrackersAndReturnError error: NSErrorPointer) -> Int
```

## Parameters

- `error`: An error that contains the reason why a failure occurs.

## Return Value

Return Value The maximum number of trackers given a combination; or 0 if such combination doesn’t exist.