Fetching list of items always times out after 60 seconds

Question

I am fetching a list of items using Alamofire and Promisekit. Some items take longer to get than others. I have set the timeout in alamoFireManager to 180 seconds, however 60 seconds after the first getRemoteItem is called, all the remaining calls for items which have not been fetched in the list will fall into the print("IN FAIL 2"). The error reads `

responseSerializationFailed(reason: Alamofire.AFError.ResponseSerializationFailureReason.jsonSerializationFailed(error: Error Domain=NSCocoaErrorDomain Code=3840 "Invalid value around line 1, column 0." UserInfo={NSDebugDescription=Invalid value around line 1, column 0., NSJSONSerializationErrorIndex=0}))

The initial getItems call will call for each item in parallel which is where I am guessing the problem may be but I cant figure out a workaround for this or why the 180 second timeout is not respected.

func getItems(ids:[Int]) -> [Promise<Bool>] {
    let totalCount = ids.count
    
    return ids.map { index -> Promise<Bool> in
        return firstly {
            getRemoteItem(id: index, totalCount: totalCount)
        }
    }
}


func getRemoteItem(id:Int, totalCount:Int) -> Promise<Bool> {
    let headers = ["Authorization": "JWT \(userToken)"]
    return Promise { seal in

        let url = baseURL + "/api/items"
        let itemParams: Parameters = ["item_id": id]
        
        alamoFireManager!.request(URL(string: url)!, method: .post, parameters: itemParams, encoding: JSONEncoding.default, headers: headers).responseJSON { response in
            switch response.result {
            case .success:
                if let jsonObject = response.result.value {
                    firstly {
                        self.saveItemToLocalStorage(jsonObject: jsonObject as! [String: Any], responseData: response.data!, totalCount: totalCount)
                    }.done { status in
                        seal.fulfill(status)
                    }.catch { error in
                        seal.reject(error)
                    }
                } else if let error = response.error {
                    print("IN FAIL 1")
                    seal.reject(error)
                }
            case .failure(let error):
                print("IN FAIL 2")
                seal.reject(error)
            }
        }
    }
}


private lazy var alamoFireManager: SessionManager? = {
    let configuration = URLSessionConfiguration.default
    configuration.timeoutIntervalForRequest = 180
    configuration.timeoutIntervalForResource = 180
    let alamoFireManager = Alamofire.SessionManager(configuration: configuration)
    return alamoFireManager
}()