Authentication - External Libraries

I am actually working these courses to help me build a specific application in IOS. I know that in the next module, we will deal with creating an auth system. However, this app will be larger in scope and has an audience with data concerns. I have an OpenID server (using KeyCloak) and plan on handling user management through it ( as this app touches a few APIs and I want SSO).

Does anyone have experience with any of the OpenID libraries out there and would you care to recommend one?

Thanks