URLSession_with_Result.swift

extension URLSession {
    func dataTask(with url: URL, completionHandler: @escaping (Result<Data, AnyError>) -> Void) -> URLSessionTask {
        return dataTask(with: url, completionHandler: { (data, response, error) in
            if let error = error {
                let anyError = AnyError(error)
                completionHandler(Result.failure(anyError))
            } else if let data = data {
                completionHandler(Result.success(data))
            } else {
                let anyError = AnyError(NSError(domain: "my domain", code: 500, userInfo: nil))
                completionHandler(Result.failure(anyError))
            }
        })
    }
}

This extension gives you the ability to use Apple's Result on URLSession. The Result type can be found at https://github.com/apple/swift-package-manager/blob/master/Sources/Basic/Result.swift