RxSwift - Recursive Observables? - ios

Question

Learning RxSwift - Here's my Problem:
i have a webservice that fetches data using an active access token, whenever the token expired , then first call the token generate api and then call the current request to run again. so that it will have an active access token to valid results.
but i have problem in getting the response for token and then call the prev. request?
so i tried adding an observable request , then in response check if the token is invalid, then call another observable to return an active token, once token is received , call the older request again.
func apirequest(_ urlConvertible:URLRequestConvertible) -> Observable<[String:AnyObject]> {
return Observable.create({ observer -> Disposable in
let _ = Alamofire.request(urlConvertible).responseJSON
{ response in
if isTokenExpired() {
self.generateToken().subscribe(onNext: response {
self.apirequest(oldRequest)
})
}
}
return Disposables.create()
})
}
i was expecting like any Rx operators or any ideas to try?
Thanks

Answer 1

I wrote an article about how to do this: https://medium.com/#danielt1263/retrying-a-network-request-despite-having-an-invalid-token-b8b89340d29
Wrap your network calling code in something like this:
/// Builds and makes network requests using the token provided by the service. Will request a new token and retry if the result is an unauthorized (401) error.
///
/// - Parameters:
/// - response: A function that sends requests to the network and emits responses. Can be for example `URLSession.shared.rx.response`
/// - tokenAcquisitionService: The object responsible for tracking the auth token. All requests should use the same object.
/// - request: A function that can build the request when given a token.
/// - Returns: response of a guaranteed authorized network request.
public func getData<T>(response: #escaping (URLRequest) -> Observable<(response: HTTPURLResponse, data: Data)>, tokenAcquisitionService: TokenAcquisitionService<T>, request: #escaping (T) throws -> URLRequest) -> Observable<(response: HTTPURLResponse, data: Data)> {
return Observable
.deferred { tokenAcquisitionService.token.take(1) }
.map { try request($0) }
.flatMap { response($0) }
.map { response in
guard response.response.statusCode != 401 else { throw TokenAcquisitionError.unauthorized }
return response
}
.retryWhen { $0.renewToken(with: tokenAcquisitionService) }
}
The article and accompanying gist shows how to write the tokenAcquisitionService and includes unit tests.