如何从Google登录中检索年龄和性别

I've integrated Google Sign-In into my iOS app. I would like to access user's gender and age. The documentation is not clear enough to see how to do this. I've figured out that I should request the right scope. I haven't found an official list of scopes in the documentation, and I don't know which scope I should use. Also I don't know how I should retrieve the data when I get it. I would appreciate if someone help me to get this info from Google. Thanks!I've integrated Google Sign-In into my iOS app.