When my app is open, Heads Up Notification appears but if the app is background or closed, it just showing on the normal status bar.
I tried on many other resources and read also in stack overflow similar questions.
But I didn't get a useful solution yet. Is it possible to show Heads Up Notification even when the app is background?
Firebase Cloud Messaging has two types of messages:
From what you're describing it sounds like you're sending a notification
message. If you always want your application code to handle the message, so that you control how it is displayed, you'll want to send a data
message instead.
For more on messages types, see: