In June 2019 Apple presented the iOS 13 SSO extension:
The new iOS 13 Single Sign-on (SSO) extension acts as the middle man that allows native apps and safari to authenticate with an identity provider.
And there are two videos on the Apple website, one about the presentation (here, min 44:44) and one introductory (here).
I'm interested in implementing this functionality, but so far I didn't encounter any documentation nor software that actually implements it.
The only documentation I found is the ASAuthorizationSingleSignOnCredential class, which doesn't explain how to implement it.
How can I implement a single sign-on system on iOS? What classes must be used and how should I combine them?