Integration Unity as a library in native Android app

There is a problem with this example: the unload buttons actually quit the app instead of just destroying the activity. (tested on Android 5.1, API level 22)

 

We have observed that when the UnityPlayerActivity hosting the UnityPlayer object is destroyed, the UnityPlayer calls Process.killProcess(myPid) as part of it's destroy() method. This causes our application to crash and restart since UnityPlayerActivity shares the same process as the application. Is there workaround for this behavior? We do not want to run the the UnityPlayerActivity as a separate process since makes integration with our application much more complicated. Can Unity add support for both types of activities? This would make the Unity library feature much more usable by a wide variety of Android applications, which we believe is the goal of this feature.

 

We have filed a bug report for the Unity Player crashing when performing 'Unload' in the NativeApp since the UnityPlayerActivity calls Process.killProcess instead of exiting cleanly: Case 1163573

 

Tried this out right now and it seems to work great!
One weird thing I noticed... I see two "NativeApp" apps installed on my test android device when I build / deploy the NativeApp project from AndroidStudio.

When I tap on one of them, it launches the Native app correctly and I can go back and forth between Unity and the Android view. But if I launch the other NativeApp app, it launches me straight into the Unity view (i.e. with the spinning cube) and skips the whole Native app layer (obviously, I don't see the native buttons in the middle as well). If I click on the Unity button to take me back to the MainView, I get a NullReference in showHostMainWindow probably beacuse the Main View does not even exist.

Dev / Test environment: Pixel 2 XL running Android 9 pie. I think I built both the UnityLibrary and the NativeApp using SDK API 28 (Pie). Not sure if this is related but when I tried to do the Gradle sync, after modifying the gradle scripts, it complained that the minSDK version of the NativeApp project was 16 while the minSDK version of the UnityLibrary was 19. So, I changed the NativeApp minSDK value to 19 to get it to build / deploy

Did I mess something up? Or is it expected that two apps get installed on the device, one native app and another the UnityLibrary?

 

Hi,

nice to see such a feature coming with Unity. Also a very nice and detailed explanation, thanks for that.
However I wanted to mention that I had to add a string to my strings.xml with name game_view_content_description in order to get it running.
If the string was not defined the UnityActivity crashed when starting it.

Thought I leave it here in case someone faces the same issue.

 

It got me too - hopefully this is in big, bold letters in the documentation. ;P

 

Any plans to add iOS support in the same way?

 

@robin_notts
I didn't try yet but iOS should already be supported, see https://forum.unity.com/threads/integration-unity-as-a-library-in-native-ios-app.685219/

 

Thanks for this integration.

To make it work on my own project, I needed in addition to add

<string name="game_view_content_description">Game view</string>

to my app's strings.xml file

and

Code (CSharp):

1. defaultConfig {
2.         ndk {
3.             abiFilters 'armeabi-v7a', 'x86'
4.         }
5.     }

to my app build.gradle file.
Otherwise, the app crashed with following error :

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mycompany.myapp/com.unity3d.player.UnityPlayerActivity}: android.content.res.Resources$NotFoundException: String resource ID #0x0

 

Not sure if this is the place to ask, but where could I find more information about combining this with AR Foundation? (supposedly one of the use-cases of Unity as a library). I managed to put my own game into the example app provided here without encountering any problems, but I'm now trying to put the AR example explained here: https://www.youtube.com/embed/ml9qVRdEH4k into the android app and I'm encountering the following error:

ERROR: Unable to resolve dependency for ':unityLibrary@debug/compileClasspath': Could not find :arcore_client:

Can anyone here give me any guidance on how to fix this, or what to google?

EDIT:

I managed to resolve the error by changing:
The dependencies in unityLibrary's build.gradle to

Code (CSharp):

1. dependencies {
2.     implementation fileTree(dir: 'libs', include: ['*.jar'])
3.     compile files('libs/arcore_client.aar')
4.     compile files('libs/unityandroidpermissions.aar')
5.     compile files('libs/UnityARCore.aar')
6. }

Now it compiles can open the app, but crashes on pressing the show unity button with the following error

No implementation found for void com.unity3d.player.UnityPlayer.nativeRestartActivityIndicator() (tried Java_com_unity3d_player_UnityPlayer_nativeRestartActivityIndicator and Java_com_unity3d_player_UnityPlayer_nativeRestartActivityIndicator__)

EDIT:

Switching to IL2CCP, and turning off Instant Run in Android Studio resolves all error and lets me use launch the AR Core example, very nice.