I have an SMS app that maintains its own SMS database, separate from the main system database used by Messages and other typical SMS apps. I would like to make it so that when another app sends an SMS (such as Google Now, or MightyText, or other GUI-less methods for sending an SMS) that message is imported into the app I'm working on. To do this, I need to trigger an action when an SMS is sent and/or when an outgoing SMS is saved to the system SMS database.
Is there a broadcast intent I can register to listen for to catch this? If not, what's the lowest overhead way to watch for and react to this event?
The IFTTT and Tasker apps can listen for sent SMSes, so I know it's possible. Unfortunately neither are open source, so I can't see how they do it.