---
title: "init(protectionSpace:proposedCredential:previousFailureCount:failureResponse:error:sender:)"
framework: foundation
role: symbol
role_heading: Initializer
path: "foundation/urlauthenticationchallenge/init(protectionspace:proposedcredential:previousfailurecount:failureresponse:error:sender:)"
---

# init(protectionSpace:proposedCredential:previousFailureCount:failureResponse:error:sender:)

Initializes an authentication challenge from parameters you provide.

## Declaration

```swift
init(protectionSpace space: URLProtectionSpace, proposedCredential credential: URLCredential?, previousFailureCount: Int, failureResponse response: URLResponse?, error: (any Error)?, sender: any URLAuthenticationChallengeSender)
```

## Parameters

- `space`: The protection space for the authentication challenge. This provides additional information about the authentication request, such as the host, port, authentication realm, and so on.
- `credential`: The proposed credential, or nil.
- `previousFailureCount`: The total number of previous failures for this request, including failures for other protection spaces.
- `response`: An instance of doc://com.apple.foundation/documentation/Foundation/URLResponse containing the server response that caused you to generate an authentication challenge, or nil if no response object is applicable to the challenge.
- `error`: An NS``Error instance describing the authentication failure, or nil if it is not applicable to the challenge.
- `sender`: The object that initiated the authentication challenge (typically, the object that called this method).

## Return Value

Return Value A new authentication challenge object, with the given properties.

## Discussion

Discussion Most apps don’t create URLAuthenticationChallenge instances themselves. Instead, they handle received challenges in the urlSession(_:task:didReceive:completionHandler:) method of URLSessionTaskDelegate. However, you might need to create authentication challenge objects when adding support for custom networking protocols, as part of your custom URLProtocol subclasses.

## See Also

### Creating an authentication challenge instance

- [init(authenticationChallenge:sender:)](foundation/urlauthenticationchallenge/init(authenticationchallenge:sender:).md)