---
title: "fileWrapper(ofType:)"
framework: appkit
role: symbol
role_heading: Instance Method
path: "appkit/nsdocument/filewrapper(oftype:)"
---

# fileWrapper(ofType:)

Creates and returns a file wrapper that contains the contents of the document, formatted to the specified type.

## Declaration

```swift
func fileWrapper(ofType typeName: String) throws -> FileWrapper
```

## Parameters

- `typeName`: The string that identifies the document type.

## Return Value

Return Value A file wrapper containing the document contents, or, if the file wrapper could not be created, nil.

## Discussion

Discussion For backward binary compatibility with OS X v10.3 and earlier, if fileWrapperRepresentationOfType: is overridden, the default implementation of this method instead invokes [self fileWrapperRepresentationOfType:typeName]. note: In Swift, this method is marked with the throws keyword to indicate that it throws an error in cases of failure. When overriding this method, use the throw statement to throw an NSError, as described in Error Handling in The Swift Programming Language and About Imported Cocoa Error Parameters.

## See Also

### Writing the Document’s Content

- [canAsynchronouslyWrite(to:ofType:for:)](appkit/nsdocument/canasynchronouslywrite(to:oftype:for:).md)
- [unblockUserInteraction()](appkit/nsdocument/unblockuserinteraction().md)
- [write(to:ofType:)](appkit/nsdocument/write(to:oftype:).md)
- [writeSafely(to:ofType:for:)](appkit/nsdocument/writesafely(to:oftype:for:).md)
- [data(ofType:)](appkit/nsdocument/data(oftype:).md)
- [write(to:ofType:for:originalContentsURL:)](appkit/nsdocument/write(to:oftype:for:originalcontentsurl:).md)
- [save(to:ofType:for:delegate:didSave:contextInfo:)](appkit/nsdocument/save(to:oftype:for:delegate:didsave:contextinfo:).md)
- [save(to:ofType:for:completionHandler:)](appkit/nsdocument/save(to:oftype:for:completionhandler:).md)
- [fileAttributesToWrite(to:ofType:for:originalContentsURL:)](appkit/nsdocument/fileattributestowrite(to:oftype:for:originalcontentsurl:).md)
- [NSDocument.SaveOperationType](appkit/nsdocument/saveoperationtype.md)