Building plug-ins for desktop platforms

Plug-ins for desktop platforms are libraries of native code written in C, C++ and Objective C. This page describes plug-ins for Windows, macOS and Linux. For further information see documentation on Native plug-ins.

macOS plug-ins

You can deploy macOS plug-ins as bundles or, if you are using IL2CPP, loose C++ files which you can use [DllImport(“__Internal”)] syntax to invoke. For further information on loose C++ plug-ins see documentation on C++ source code plugins for IL2CPP.

To create the bundle project with XCode, open XCode 11 and select File > New > Project, then navigate to macOS > Framework & Library > Bundle. For more information on working with XCode see Apple’s documentation on XCode.

You must build your plug-in as a universal binary that contains 64-bit architectures. Alternatively, you can provide separate dylib files. If you are using C++ (.cpp) or Objective-C (.mm) to implement the plug-in then you must make sure you declare the functions with C linkage to avoid name mangling issues.

extern "C"
{
  float FooPluginFunction ();
}

Windows plug-ins

Plug-ins on Windows are either .dll files with exported functions, or loose C++ files if you are using IL2CPP. You can use most languages and development environments that can create .dll files to create plug-ins. You must declare any C++ functions with C linkage to avoid name mangling issues.

Linux plug-ins

Plug-ins on Linux are .so files with exported functions. While these libraries are typically in C or C++, you can use any language. As with the other platforms, you must declare any C++ functions with C linkage to avoid name mangling issues.

Managing plug-ins inside Unity

In Unity, the Plugin Inspector manages your plug-ins. To access the Plugin Inspector, select a plug-in file in the Project window. For Standalone platforms you can choose the CPU architecture with which the library is compatible. For cross platform plug-ins you must include the .bundle file (for macOS), the .dll file(for Windows), and the .so file (for Linux). Unity automatically picks the right plug-in for the target platform and includes it with the player. For further information see documentation on the Plugin Inspector.

Using your plug-in from C#

Once you have built the bundle, you must place it in the Assets folder (or the appropriate architecture-specific sub-directory) in your Unity Project. Unity then finds it by name when you define a function like the following in the C# script: [DllImport ("PluginName")] private static extern float FooPluginFunction ();

Note: PluginName should not include the library prefix nor file extension. For example, the actual name of the plug-in file would be PluginName.dll on Windows and libPluginName.so on Linux.

Example plug-ins