title: Apple Sign In below ios13
body: <p>I have a question about Apple Sign In. In App Store Guideline there We can found that Apple Sign in is mandatory when app uses third party sign in options (like google or facebook).As I know Apple sign in mechanism was added in ios 13. What if I want to build app with minimum version of iOS set to 11 or 12? Still I need to implement Apple sign in (and if so, how?)?</p>