Implementation of Alamofire RequestInterceptor with refreshToken

Question

I'm trying to handle 401 unauthorized request with Alamofire (5.6.1)

which Alamofire implementation should I use?

At first login post method I'm getting that kind of data:

 {
   "authToken": "auth12345",
   "refreshToken": "refresh6789"
 }

after that for each request to my API end point (ex. baseURL + " /user/api/user-address ")
I'm using that header with authToken

["Authorization": "Bearer \(authToken)", "Accept": "application/json"]

At the moment of expiration of authToken I starting to receive 401 code - which is unauthorized request.

To get new authToken I have to make request with refreshToken to specific endpoint which is:

baseURL + /auth/api/refresh-token

By reading alamofire doc I'm a bit confusing which implementation RequestInterceptor I have to go with:

RequestAdapter, RequestRetrier - says to implement:

1. func adapt(_ urlRequest: URLRequest, for session: Session, completion: @escaping (Result<URLRequest, Error>) -> Void)

2. func retry(_ request: Request, for session: Session, dueTo error: Error, completion: @escaping (RetryResult) -> Void)

but as I see example:

func adapt(_ urlRequest: URLRequest, for session: Session, completion: @escaping (Result<URLRequest, Error>) -> Void) {
    var urlRequest = urlRequest
    urlRequest.headers.add(.authorization(bearerToken: accessToken))

    completion(.success(urlRequest))
}

it's just modifies header ( headers.add ) with same expired accessToken and not gives you option

to make a call to specific endpoint with refreshToken

There also example of implementation class OAuthAuthenticator: Authenticator and

struct OAuthCredential: AuthenticationCredentia which is also not visible for me for providing

mechanism for dedicated endpoint to refresh authToken with refreshToken.

Answer 1

If you can check whether your token is expired ahead of time, you can implement the refresh in the adapt method:

func adapt(_ urlRequest: URLRequest, for session: Session, completion: @escaping (Result<URLRequest, Error>) -> Void) {
  // Check token expiration.
  // If expired, call refresh, then call completion.
  // If not expired, adapt the request like normal and call completion.
}

If you can't do that, just implement the normal adapt you already have and implement the refresh in retry :

func retry(_ request: Request, for session: Session, dueTo error: Error, completion: @escaping (RetryResult) -> Void) {
  // If error is 401, refresh the tokens, then call the completion handler to trigger retry.
  // Retrying the request should then call adapt with the new token.
  // If the error isn't 401 and you don't want to retry, call completion(.doNotRetry).
}