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# filenameExtension(_:isValidForType:)

Returns whether the specified filename extension is appropriate for the Uniform Type Identifier (UTI).

```
func filenameExtension(_ filenameExtension: String, isValidForType typeName: String) -> Bool
```

## Parameters

`filenameExtension`

A string containing the filename extension.

`typeName`

A string containing the UTI.

## Return Value

<doc://com.apple.documentation/documentation/Swift/true> if `fileNameExtension` is a valid extension for `typeName`; otherwise, <doc://com.apple.documentation/documentation/Swift/false>.

## Discussion

You can safely call this method from any thread of your app.

---

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