<!--
{
  "availability" : [
    "iOS: 3.0.0 -",
    "iPadOS: 3.0.0 -",
    "macCatalyst: 13.1.0 -",
    "macOS: 10.3.0 -",
    "tvOS: 9.0.0 -",
    "visionOS: 1.0.0 -",
    "watchOS: 2.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "Foundation",
  "identifier" : "/documentation/Foundation/ValueTransformer/reverseTransformedValue(_:)",
  "metadataVersion" : "0.1.0",
  "role" : "Instance Method",
  "symbol" : {
    "kind" : "Instance Method",
    "modules" : [
      "Foundation"
    ],
    "preciseIdentifier" : "c:objc(cs)NSValueTransformer(im)reverseTransformedValue:"
  },
  "title" : "reverseTransformedValue(_:)"
}
-->

# reverseTransformedValue(_:)

Returns the result of the reverse transformation of a given value.

```
func reverseTransformedValue(_ value: Any?) -> Any?
```

## Parameters

`value`

The value to reverse transform.

## Return Value

The reverse transformation of `value`.

## Discussion

The default implementation raises an exception if [`allowsReverseTransformation()`](/documentation/Foundation/ValueTransformer/allowsReverseTransformation()) returns <doc://com.apple.documentation/documentation/Swift/false>; otherwise it will invoke [`transformedValue(_:)`](/documentation/Foundation/ValueTransformer/transformedValue(_:)) with `value`.

A subclass should override this method if they require a reverse transformation that is not the same as simply reapplying the original transform (as would be the case with negation, for example). For example, if a value transformer converts a value in Fahrenheit to Celsius, this method would converts a value from Celsius to Fahrenheit.

---

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)