Unable to get FedAuth cookie every time from WKWebView container during SharePoint site authentication in Objective-C

I am not getting FedAuth cookie every time from WKWebView container (WKHTTPCookieStore) during SharePoint site authentication in my Objective-C application. I have also implemented cookiesDidChangeInCookieStore method in my app. Normally cookies count should be increased. But sometimes it decreases and FedAuth cookie is not available in WKHTTPCookieStore for this case.
Any idea why some times FedAuth cookie is not available in WKHTTPCookieStore during SharePoint site authentication?
Unable to get FedAuth cookie every time from WKWebView container during SharePoint site authentication in Objective-C
 
 
Q