---
title: "knownClassifications(forRevision:)"
framework: vision
role: symbol
role_heading: Type Method
path: "vision/vnclassifyimagerequest/knownclassifications(forrevision:)"
---

# knownClassifications(forRevision:)

Requests the collection of classifications that the Vision framework recognizes.

## Declaration

```swift
class func knownClassifications(forRevision requestRevision: Int) throws -> [VNClassificationObservation]
```

## Parameters

- `requestRevision`: The revision of the request for which to report classifications.

## Return Value

Return Value An array of classifications for the revision, or nil if an error occurs.

## See Also

### Accessing Results

- [supportedIdentifiers()](vision/vnclassifyimagerequest/supportedidentifiers().md)
- [results](vision/vnclassifyimagerequest/results.md)
- [VNClassificationObservation](vision/vnclassificationobservation.md)