iOS Swift - How to use Facebook Sign Up and Login -

this high level architectural question.

i want use "sign facebook" , "log in facebook" in ios app.

questions:

1. i find many tutorials logging in facebook not getting sign facebook, tutorial "signup facebook".

2. how can use sign facebook in app? in, architecture? need send server? need store user in server's db?

after checking spotify's "signup facebook" understanding is, when user clicks on sign facebbok, still asked facebook login signup screen pre-filled basic information phone, email, first , last name etc, can use on app sign user.

next time when user logs in using facebook validate if has signup or not

am thinking right? corrections? feedback?

if you're using facebook login sole purpose of being easy way users sign up/log in app, app rejected apple. need using facebook application features go beyond basic profile information , sharing.

i went through during apple app store review process , think it's worth noting here. little warning think save time.