I want to show unread notification count on my app icon when app is not opened. this post seems to be close but it is 3 years old. Has there been any change on this or I should go with solutions provided in the accepted answer?
Unfortunately you cant achieve this for all android devices.
Certain manufacturers (e.g. Samsung or Sony) have included this functionality into their customised Android launchers. Also some 3rd-party launchers (e.g. Nova Launcher) have included an API to accomplish this.
Some related posts for more information:
And some libraries that might be helpful:
and more...