I know that it is possible (Android GCM: same sender id for more application) but I don't know how to make it happen.
GCM is already working properly on our android app. Now we want to use it in our ios app too. But when I try to register ios app for gcm in google developer console, it always registers a new app and provides a new sender id.
NOTE: No plan to use Firebase Cloud Messaging(FCM) yet.