---
title: "init(filenameExtension:)"
framework: uniformtypeidentifiers
role: symbol
role_heading: Initializer
path: "uniformtypeidentifiers/uttypereference/init(filenameextension:)"
---

# init(filenameExtension:)

Creates a type that represents the specified filename extension.

## Declaration

```swift
convenience init?(filenameExtension: String)
```

## Parameters

- `filenameExtension`: The filename extension.

## Discussion

Discussion If the system recognizes the filename extension, the intializer returns the corresponding type; otherwise, the initializer returns a dynamic type whose isDeclared and isPublic properties are both set to false.

## See Also

### Creating a type

- [init(_:)](uniformtypeidentifiers/uttypereference/init(_:).md)
- [init(mimeType:)](uniformtypeidentifiers/uttypereference/init(mimetype:)-1txq0.md)
- [init(mimeType:conformingTo:)](uniformtypeidentifiers/uttypereference/init(mimetype:conformingto:).md)
- [init(filenameExtension:conformingTo:)](uniformtypeidentifiers/uttypereference/init(filenameextension:conformingto:).md)
- [init(tag:tagClass:conformingToType:)](uniformtypeidentifiers/uttypereference/init(tag:tagclass:conformingtotype:).md)
- [init(exportedAs:)](uniformtypeidentifiers/uttypereference/init(exportedas:).md)
- [init(exportedAs:conformingTo:)](uniformtypeidentifiers/uttypereference/init(exportedas:conformingto:).md)
- [init(importedAs:)](uniformtypeidentifiers/uttypereference/init(importedas:).md)
- [init(importedAs:conformingTo:)](uniformtypeidentifiers/uttypereference/init(importedas:conformingto:).md)