eeduard

Оказалось все проще, не сделал связь в Сториборде между WebView и кодом во ViewController
Вдруг кому надо

import UIKit
import WebKit

class ViewController: UIViewController {

let url = URL(string: "https://название сайта")!


@IBOutlet weak var webview: WKWebView!

override func viewDidLoad() {

    super.viewDidLoad()
    webview.load(URLRequest(url: self.url))
    webview.uiDelegate = self
    webview.navigationDelegate = self
    webview.translatesAutoresizingMaskIntoConstraints = false
    NSLayoutConstraint.activate([
        webview.leadingAnchor.constraint(equalTo: view.leadingAnchor),
        webview.trailingAnchor.constraint(equalTo: view.trailingAnchor),
        webview.topAnchor.constraint(equalTo: view.topAnchor),
        webview.bottomAnchor.constraint(equalTo: view.bottomAnchor)
    ])
}}
extension WKWebView {

enum PrefKey {
    static let cookie = "cookies"
}

func writeDiskCookies(for domain: String, completion: @escaping () -> ()) {
    fetchInMemoryCookies(for: domain) { data in
        print("write data", data)
        UserDefaults.standard.setValue(data, forKey: PrefKey.cookie + domain)
        completion();
    }
}


 func loadDiskCookies(for domain: String, completion: @escaping () -> ()) {
    if let diskCookie = UserDefaults.standard.dictionary(forKey: (PrefKey.cookie + domain)){
        fetchInMemoryCookies(for: domain) { freshCookie in

            let mergedCookie = diskCookie.merging(freshCookie) { (_, new) in new }

            for (cookieName, cookieConfig) in mergedCookie {
                let cookie = cookieConfig as! Dictionary<String, Any>

                var expire : Any? = nil

                if let expireTime = cookie["Expires"] as? Double{
                    expire = Date(timeIntervalSinceNow: expireTime)
                }

                let newCookie = HTTPCookie(properties: [
                    .domain: cookie["Domain"] as Any,
                    .path: cookie["Path"] as Any,
                    .name: cookie["Name"] as Any,
                    .value: cookie["Value"] as Any,
                    .secure: cookie["Secure"] as Any,
                    .expires: expire as Any
                ])

                self.configuration.websiteDataStore.httpCookieStore.setCookie(newCookie!)
            }

            completion()
        }

    }
    else{
        completion()
    }
}

func fetchInMemoryCookies(for domain: String, completion: @escaping ([String: Any]) -> ()) {
    var cookieDict = [String: AnyObject]()
    WKWebsiteDataStore.default().httpCookieStore.getAllCookies { (cookies) in
        for cookie in cookies {
            if cookie.domain.contains(domain) {
                cookieDict[cookie.name] = cookie.properties as AnyObject?
            }
        }
        completion(cookieDict)
    }
}}
extension ViewController: WKUIDelegate, WKNavigationDelegate {
func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
   //load cookie of current domain
    webView.loadDiskCookies(for: url.host!){
        decisionHandler(.allow)
    }
}

public func webView(_ webView: WKWebView, decidePolicyFor navigationResponse: WKNavigationResponse, decisionHandler: @escaping (WKNavigationResponsePolicy) -> Void) {
   //write cookie for current domain
    webView.writeDiskCookies(for: url.host!){
        decisionHandler(.allow)
    }
}
}