I added an ASWebAuthenticationSession to iOS app due to receiving message "A valid client certificate is required" from URL requests. It opens Safari, the user selects their certificate and the web server authenticates. I get a successfull callback URL on the iOS app. I was under the impression, after the web session was started, I could run GET resquests using URLSession. However, I am receiving the same message that it needs a valid certificate. I am pretty new to iOS development. Any suggestions? Thanks!