I have an app doing a facebook login, which works well, but everytime I reopen it I have to connect again to facebook to do the sign-in. I'm also using google sign-in sdk where I can call the function gSignIn.signInSilently(), is there something similar for facebook? I found this for the javascript sdk but I don't know if it's possible for the ios SDK and how to use it in swift...
The Facebook SDK automatically maintains the login state, which can be confirmed by checking for the access token.
You can check for the access using the following method:
FBSDKAccessToken.currentAccessToken()
You can check for the presence of the token which would mean that the user is logged in.
Check the docs for more details.