How to create a system app for custom ROM

Question

We have a custom ROM for a device we are making and what I want to do is make our own custom Settings app to replace the settings app that comes already built in android.

I cant really find any documentation on how to even create a system app. It does not appear you can create it in Android Studio, I tried looking on the AOSP site and didnt find anything there related to creating system apps. The few things I did find were on here where you would put android:sharedUserId="android.uid.system" in your manifest and then has to be signed with the same key as the ROM but after that I cant find anything.

The settings app I want to create would need access to the framework.jar to be able to use the hidden framework API's.

Does anyone have any information or know where I can find this information on how to go about actually creating a system app?

Answer 1

You may want to research how to make a Device Tree Overlay (dto). Basically it is your code, reformatting the base code, into what you want. https://source.android.com/devices/architecture/dto?hl=en

Answer 2

Since you said you use Gradle, you should put first build you apk and put them in you vender folder, and next important thing is to create a mk/bp file to tell the Android build system how to deal with this pre-built apk.

PS If you system app highly depends on Android hidden api, make sure you have the right version of framework.jar in you Android Studio project, or, as what I alway did, create apps directly in AOSP, in this case, you can just check the code structure of the original Settings app in AOSP

this tutorial may help you.