如何实现URLSessionDelegate允许自签名证书？ （式IO / SWIFT）

Question

I'm trying to use SocketIO to connect to a server running on my workstation from an iOS/Swift app. The certificate I'm using on the server is self-signed and I'm using the following code to connect:

import UIKit
import SocketIO


class ViewController: UIViewController, URLSessionDelegate {
    let socketManager = SocketManager(socketURL: URL(string:"https://my_server_url")!,
                        config: [SocketIOClientOption.log(true),
                                 SocketIOClientOption.forcePolling(true),
                                 SocketIOClientOption.selfSigned(true),
                                 SocketIOClientOption.sessionDelegate(self)])


    func URLSession(_ session: URLSession,
                    task: URLSessionTask,
                    didReceive challenge: URLAuthenticationChallenge,
                    completionHandler: (URLSession.AuthChallengeDisposition, URLCredential?)
        -> Void) {
        print("didReceive challenge")
        completionHandler(.useCredential, URLCredential(trust: challenge.protectionSpace.serverTrust!))
    }

Unfortunately I get the following error: Argument type '(ViewController) -> () -> (ViewController)' does not conform to expected type 'URLSessionDelegate' where I set the sessionDelegate to self.

I'm not sure why that is the case since all funcs in URLSessionDelegate are optional and I thought that my implementation of URLSession conformed to the protocol. I apologise if I'm doing something dumb but I'm new to iOS and Swift and I've been looking for an answer for hours with no success!

Answer 1

func urlSession(_ session: URLSession, task: URLSessionTask, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
    // Pass test server with self signed certificate
    if challenge.protectionSpace.host == "self-signed-certificate.server.com" {
        completionHandler(.useCredential, URLCredential(trust: challenge.protectionSpace.serverTrust!))
    } else {
        completionHandler(.performDefaultHandling, nil)
    }
}