As titled. Want to have a function that makes the app automatically pop up when someone uses his phone (i.e. start the app when he unlock the screen). Is there any library which can do that?
I don't think such a library exists because you can do that simply or registering a static intent receiver or using a background service watching the PhoneEvents. That service would start the Activity at the UserPresent event, for example.
You have all the tools already