---
title: "filePromiseProvider(_:writePromiseTo:completionHandler:)"
framework: appkit
role: symbol
role_heading: Instance Method
path: "appkit/nsfilepromiseproviderdelegate/filepromiseprovider(_:writepromiseto:completionhandler:)"
---

# filePromiseProvider(_:writePromiseTo:completionHandler:)

Writes the contents of a promise to the specified URL.

## Declaration

```swift
nonisolated func filePromiseProvider(_ filePromiseProvider: NSFilePromiseProvider, writePromiseTo url: URL, completionHandler: @escaping @Sendable ((any Error)?) -> Void)
```

```swift
nonisolated func filePromiseProvider(_ filePromiseProvider: NSFilePromiseProvider, writePromiseTo url: URL) async throws
```

## Parameters

- `filePromiseProvider`: The file promise provider.
- `url`: The destination URL to write to.
- `completionHandler`: A completion handler to execute after the file has been written.

## Discussion

Discussion This method is called after the drag is complete. The request executes on the OperationQueue supplied by operationQueue(for:). Call the completion handler with the file contents wrapped in NSFileCoordinator.  Be sure to write your file to the input url parameter.

## See Also

### Handling File Promises

- [filePromiseProvider(_:fileNameForType:)](appkit/nsfilepromiseproviderdelegate/filepromiseprovider(_:filenamefortype:).md)
- [operationQueue(for:)](appkit/nsfilepromiseproviderdelegate/operationqueue(for:).md)