---
title: "urlSession(_:didReceive:completionHandler:)"
framework: foundation
role: symbol
role_heading: Instance Method
path: "foundation/urlsessiondelegate/urlsession(_:didreceive:completionhandler:)"
---

# urlSession(_:didReceive:completionHandler:)

Requests credentials from the delegate in response to a session-level authentication request from the remote server.

## Declaration

```swift
optional func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping @Sendable (URLSession.AuthChallengeDisposition, URLCredential?) -> Void)
```

```swift
optional func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge) async -> (URLSession.AuthChallengeDisposition, URLCredential?)
```

## Parameters

- `session`: The session containing the task that requested authentication.
- `challenge`: An object that contains the request for authentication.
- `completionHandler`: A handler that your delegate method must call. This completion handler takes the following parameters:: disposition—One of several constants that describes how the challenge should be handled. credential—The credential that should be used for authentication if disposition is NSURLSessionAuthChallengeUseCredential, otherwise NULL.

## Mentioned in

Performing manual server trust authentication

## Discussion

Discussion This method is called in two situations: When a remote server asks for client certificates or Windows NT LAN Manager (NTLM) authentication, to allow your app to provide appropriate credentials When a session first establishes a connection to a remote server that uses SSL or TLS, to allow your app to verify the server’s certificate chain If you do not implement this method, the session calls its delegate’s urlSession(_:task:didReceive:completionHandler:) method instead. note: This method handles only the NSURLAuthenticationMethodNTLM, NSURLAuthenticationMethodNegotiate, NSURLAuthenticationMethodClientCertificate, and NSURLAuthenticationMethodServerTrust authentication types. For all other authentication schemes, the session calls only the urlSession(_:task:didReceive:completionHandler:) method.

## See Also

### Handling authentication challenges

- [URLSession.AuthChallengeDisposition](foundation/urlsession/authchallengedisposition.md)