Integrating Unity into Android applications

This page describes how to integrate the Unity Runtime Library into Android applications using the Unity as a Library feature.

You can use this feature to include Unity-powered features, such as 3D/2D Real-Time Rendering, AR Experience, 3D model interaction, or 2D mini-games, into your application. The Unity Runtime Library exposes controls to manage when and how to load, activate, and unload content within the application.

Important: If you upgrade your project to Unity 2019.4 or above, the introduction of Unity as a Library might require you to adapt native and managed plug-insA set of code created outside of Unity that creates functionality in Unity. There are two kinds of plug-ins you can use in Unity: Managed plug-ins (managed .NET assemblies created with tools like Visual Studio) and Native plug-ins (platform-specific native code libraries). More info
See in Glossary to work properly for Android. Plug-ins that make changes to GradleAn Android build system that automates several build processes. This automation means that many common build errors are less likely to occur. More info
See in Glossary manifests need to use the the Gradle changes outlined in Using Unity as a library in native iOS/Android apps.

How it works

You don’t need to do anything different when you build your Gradle project from Unity.

Every Android Gradle project that Unity generates has the following structure:

• A library part in the unityLibrary module that you can integrate into any other Gradle project. This contains the Unity runtime and Player data.
• A thin launcher part in the launcher module that contains the application name and its icons. This is a simple Android application that launches Unity. You can replace this module with your own application.

To integrate Unity into another Android Gradle project, you must include the unityLibrary module of the generated Android Gradle project in your Android Unity Project through the settings.gradle file.

This repository contains example Projects and plug-ins that demonstrate how to integrate Unity into an Android app, along with further documentation.

To control a Player, relay an Intent to launch Unity activity and extend it if needed. For more information, see Android developer documentation on Intents and Intent Filters. You can also use the UnityPlayer Java API.

IUnityPlayerLifecycleEvents

IUnityPlayerLifecycleEvents provides a way to interact with two important lifecycle events of the Unity Player:

• Unload - The application calls IUnityPlayerLifecycleEvents.onUnityPlayerUnloaded when Application.Unload or UnityPlayer.unload() unloads the Unity Player. This puts the Unity Player in a paused state where it unloads all ScenesA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
  See in Glossary, but keeps everything else loaded in the memory.
• Quit - The application calls IUnityPlayerLifecycleEvents.onUnityPlayerQuitted when the Unity Player quits. The process that was running Unity ends after this call.

You can pass an instance of IUnityPlayerLifecycleEvents to the UnityPlayer constructor, or to override methods in subclasses of UnityPlayer and UnityPlayerActivity.

Limitations

Unity doesn’t control the runtime lifecycle, so Unity as a Library might not work for all possible use cases. Known limitations include:

• Unity as a Library only supports full-screen rendering, and doesn’t support rendering on part of the screen.
• You can’t load or integrate more than one instance of the Unity runtime.
• You might need to adapt third-party plug-ins (both native and managed) to work with the Unity runtime.
• Unity as a Library isn’t compatible with the Xamarin app platform.

Additional resources

• Using Unity as a Library in other applications