Android and specific notifications

Question

I want my app to notify users of specific events that can occur at a certain time.

I know how to send a notification knowing the exact time of it, but things get a little complicated for me when I want to trigger notifications at times that are unknown at app install (notifications whose time can change or which depend on a specific event).

Here are two cases in which I don't know how to trigger a notification :

• Send a notification every day at a time that can change from day to day. Say I want to notify users that it's sunrise time, do I need a Service to run permanetly an calculate for each day the time of sunset and trigger a notification when the time comes ?

• Send a notification everytime something new in the community occurs. I don't want to notify users of an update, but just of a particular event at a certain time. How do I send notifications to them?

How can I achieve this ?

Thanks !

Answer 1

For your first option i would use a AlarmManager. It will execute a function on a specific time, that can be set on app startup. Everytime the AlarmManager executes and sends a notification to the user, it should re-calculate the next message time and reset the AlarmManager. ( see how to reset here )

For your second scenario you could use a library like OneSignal. It's a verry usefull library for registering users for pushnotifications and sending messages from a website to your users. You can choose groups of users or specific users for sending messages and you can customize the look of your pushmessages ( add buttons, images, .. etc).