How can I send a message to my user in my app that should be display on screen. Every time when I send a new message
Are they individual messages? Have they to display immediately as you send them?
Yes they are individual,yes they have to display immediately
You could use a firebase for that. But even this should work. It just depends on how secure it has to be.
I send you the link for how to ask a question else other users will have to keep asking questions to you for more info like what have you tried yourself?