There are extra steps to be able to get notification when working on iOS.
First login to your apple developer account.
Next create a new key if you don't have a key already.
Add the key name and enable Apple Push Notifications service (APNs)
After this, there will be a screen to download the generate key for you.
WARNING!!! - Please make sure the downloaded file is kept safe, because you can only download it once.
After downloading the key from apple dashboard. You have to upload the key to firebase, so firebase can send notification to iOS device.
Go to project setting on your firebase console
On the project settings, go to the cloud messaging tab
Select the app you want to setup
Them upload the downloaded keys previously
Do the same for the rest apps
