Thanks for your reply.
Following are the steps I am performing.
Created application in Facebook developer account.
Setup Facebook appid and secret in Connection → Social → Facebook → Settings.
Click on Try and and its working.
Now what I am doing in my application.
I have a button in my login page “Login with Facebook”.
On click this button I am opening facebook page using Facebook iOS SDK.
After successful login from facebook I am getting FBAccessToken string and this token I am passing in method below.
let auth = Auth0.authentication(clientId: APP_CLIENT_ID,
domain: APP_DOMAIN) ,
session: .shared)
auth.loginSocial(token: TOKEN_OBTAINED_FROM_FACEBOOK_AFTER_LOGIN_IN_FACEBOOK, connection: “facebook”).start
{ result in
print(result)
}