IOS application using Google OAuth2 (web application) - "Close this window."

Question

I have an OAuth2 authentication process in my UIWebView app for iOS Swift. I used the official OAuth2 JavaScript library for authentication. However, when authentication is complete, it goes to the web page with only the text saying "Please close this window." I believe he is trying to do window.close () or something like that.

In any case, my application may respond to this "Please close this window."