Multiple SSH Keys settings for different github account
create different public key
create different ssh key according the article Mac Set-Up Git
$ ssh-keygen -t rsa -C "firstname.lastname@example.org"
Below is a full tutorial on how to setup and use Googles Firebase push notification API for both Android and iOS. It is based on this earlier implementation of Googles GCM method: https://gist.github.com/prime31/5675017 - FCM is the new method and GCM will eventually be retired.
Register your app in the FCM Console: https://console.firebase.google.com (add project)