iOS WKWebview cookie problem

When I want to get a specified cookie item which response by the server with WKWebview , I have met some trouble.
The Charles tool can view the cookie item in response,When I debug the app the Safari developer storage also can view the cookie item,But I can not use iOS function to get it. Here is some test.

WKHTTPCookieStore *cookieStore = self.webView.configuration.websiteDataStore.httpCookieStore;
    [cookieStore getAllCookies:^(NSArray<NSHTTPCookie *> * Nonnull cookies) {
      for (NSHTTPCookie *cookie in cookies) {
NSLog(@"CookieStore cookie name is %@",cookie.name);
      }
    }];

 [[NSHTTPCookieStorage sharedHTTPCookieStorage].cookies enumerateObjectsUsingBlock:^(NSHTTPCookie * Nonnull obj, NSUInteger idx, BOOL * Nonnull stop) {
    NSLog(@"NSHTTPCookieStorage cookie name is %@",obj.name);
  }];

 [self.webView evaluateJavaScript:@"document.cookie;" completionHandler:^(id Nullable ret, NSError * _Nullable error) {
      NSLog(@"documents cookies is %@ error is %@",ret,error);
    }];

All test log have no the cookie , If the 'WKHTTPCookieStore' or ' NSHTTPCookieStorage' are different with the Safari developer cookie storage ? If YES ,How can i get the cookie?