it is possible to leave the application in the background
what i want to do is
when a data is changed in the database, the application rings a bell but in the background
Yes, it is possible.
I have made a music app which plays music even when it is in background, but if you close it it will not work.
And the work in background is from default.
Sorry for bad english 
Hi thanks for answering
of course music if you can, but what you want to do is activate a function while you are in the background
Don’t worry, I don’t speak English either, I use google translator
How did you achieve that? I’ve made a radio app but can’t seem to keep it playing in the background.