Special folders and script compilation order Assembly definitions

Platform dependent compilation

Unity’s Platform Dependent Compilation feature consists of some preprocessor directives that let you partition your scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info

See in Glossary to compile and execute a section of code exclusively for one of the supported platforms.

You can run this code within the Unity Editor, so you can compile the code specifically for your target platform and test it in the Editor.

Platform #define directives

The platform #define directives that Unity supports for your scripts are as follows:

Define Function UNITY_EDITOR #define directive to call Unity Editor scripts from your game code. UNITY_EDITOR_WIN #define directive for Editor code on Windows. UNITY_EDITOR_OSX #define directive for Editor code on Mac OS X. UNITY_EDITOR_LINUX #define directive for Editor code on Linux. UNITY_STANDALONE_OSX #define directive to compile or execute code specifically for Mac OS X (including Universal, PPC and Intel architectures). UNITY_STANDALONE_WIN #define directive for compiling/executing code specifically for Windows standalone applications. UNITY_STANDALONE_LINUX #define directive for compiling/executing code specifically for Linux standalone applications. UNITY_STANDALONE #define directive for compiling/executing code for any standalone platform (Mac OS X, Windows or Linux). UNITY_WII #define directive for compiling/executing code for the Wii console. UNITY_IOS #define directive for compiling/executing code for the iOS platform. UNITY_IPHONE Deprecated. Use UNITY_IOS instead. UNITY_ANDROID #define directive for the Android platform. UNITY_PS4 #define directive for running PlayStation 4

See in Glossary Sony’s eighth generation video game console. UNITY_XBOXONE #define directive for executing Xbox One

See in Glossary Microsoft’s eighth generation video game console. UNITY_LUMIN #define directive for the Magic Leap OS platform. You can also use PLATFORM_LUMIN. UNITY_TIZEN #define directive for the Tizen platform. UNITY_TVOS #define directive for the Apple TV platform. UNITY_WSA #define directive for Universal Windows Platform

See in Glossary An IAP feature that supports Microsoft’s In App Purchase simulator, which allows you to test IAP purchase flows on devices before publishing your application. More info NETFX_CORE is defined when compiling C# files against .NET Core and using .NET scripting backend

See in Glossary A framework that powers scripting in Unity. Unity supports three different scripting backends depending on target platform: Mono, .NET and IL2CPP. Universal Windows Platform, however, supports only two: .NET and IL2CPP. More info UNITY_WSA_10_0 #define directive for Universal Windows Platform. Additionally WINDOWS_UWP is defined when compiling C# files against .NET Core. UNITY_WINRT Same as UNITY_WSA. UNITY_WINRT_10_0 Equivalent to UNITY_WSA_10_0 UNITY_WEBGL #define directive for WebGL

See in Glossary A JavaScript API that renders 2D and 3D graphics in a web browser. The Unity WebGL build option allows Unity to publish content as JavaScript programs which use HTML5 technologies and the WebGL rendering API to run Unity content in a web browser. More info UNITY_FACEBOOK #define directive for the Facebook platform (WebGL or Windows standalone). UNITY_ANALYTICS #define directive for calling Unity Analytics

See in Glossary A data platform that provides analytics for your Unity game. More info UNITY_ASSERTIONS #define directive for assertions control process. UNITY_64 #define directive for 64-bit platforms.

You can also compile code selectively. The options available depend on the version of the Editor that you are working on. Given a version number X.Y.Z (for example, 2.6.0), Unity exposes three global #define directives in the following formats: UNITY_X, UNITY_X_Y and UNITY_X_Y_Z.

Here is an example of #define directives exposed in Unity 5.0.1:

Define Function UNITY_5 #define directive for the release version of Unity 5, exposed in every 5.X.Y release. UNITY_5_0 #define directive for the major version of Unity 5.0, exposed in every 5.0.Z release. UNITY_5_0_1 #define directive for the minor version of Unity 5.0.1.

Starting from Unity 5.3.4, you can compile code selectively based on the earliest version of Unity required to compile or execute a given portion of code. Given the same version format as above (X.Y.Z), Unity exposes one global #define in the format UNITY_X_Y_OR_NEWER, that can be used for this purpose.

The supported #define directives are:

Define Function CSHARP_7_3_OR_NEWER Defined when building scripts with support for C# 7.3 or newer. ENABLE_MONO Scripting backend #define for Mono. ENABLE_IL2CPP Scripting backend #define for IL2CPP

See in Glossary A Unity-developed scripting back-end which you can use as an alternative to Mono when building projects for some platforms. More info NET_2_0 Defined when building scripts against .NET 2.0 API compatibility level on Mono and IL2CPP. NET_2_0_SUBSET Defined when building scripts against .NET 2.0 Subset API compatibility level on Mono and IL2CPP. NET_LEGACY Defined when building scripts against .NET 2.0 or .NET 2.0 Subset API compatibility level on Mono and IL2CPP. NET_4_6 Defined when building scripts against .NET 4.x API compatibility level on Mono and IL2CPP. NET_STANDARD_2_0 Defined when building scripts against .NET Standard 2.0 API compatibility level on Mono and IL2CPP. ENABLE_WINMD_SUPPORT Defined when Windows Runtime support is enabled on IL2CPP. See Windows Runtime Support for more details. ENABLE_INPUT_SYSTEM Defined when the Input System package is enabled in Player Settings

See in Glossary Settings that let you set various player-specific options for the final game built by Unity. More info ENABLE_LEGACY_INPUT_MANAGER Defined when the legacy Input Manager

See in Glossary Settings where you can define all the different input axes, buttons and controls for your project. More info

You use the DEVELOPMENT_BUILD #define to identify whether your script is running in a player which was built with the “Development BuildA development build includes debug symbols and enables the Profiler. More info

See in Glossary” option enabled.

You can also compile code selectively depending on the scripting back-end.

Testing precompiled code

Below is an example of how to use the precompiled code. It prints a message that depends on the platform you have selected for your target build.

First of all, select the platform you want to test your code against by going to File > Build Settings. This displays the Build Settings window; select your target platform from here.

Build Settings window with PC, Mac & Linux selected as the target platforms

Select the platform you want to test your precompiled code against and click Switch Platform to tell Unity which platform you are targeting.

Create a script and copy/paste the following code:

// C# using UnityEngine; using System.Collections; public class PlatformDefines : MonoBehaviour { void Start () { #if UNITY_EDITOR Debug.Log("Unity Editor"); #endif #if UNITY_IOS Debug.Log("Iphone"); #endif #if UNITY_STANDALONE_OSX Debug.Log("Stand Alone OSX"); #endif #if UNITY_STANDALONE_WIN Debug.Log("Stand Alone Windows"); #endif } }

To test the code, click Play Mode. Confirm that the code works by checking for the relevant message in the Unity console, depending on which platform you selected - for example, if you choose iOSApple’s mobile operating system. More info

See in Glossary, the message “Iphone” is set to appear in the console.

In C# you can use a CONDITIONAL attribute which is a more clean, less error-prone way of stripping out functions. See ConditionalAttribute Class for more information. Note that common Unity callbacks (ex. Start(), Update(), LateUpdate(), FixedUpdate(), Awake()) are not affected by this attribute because they are called directly from the engine and, for performance reasons, it does not take them into account.

In addition to the basic #if compiler directive, you can also use a multiway test in C#:

#if UNITY_EDITOR Debug.Log("Unity Editor"); #elif UNITY_IOS Debug.Log("Unity iPhone"); #else Debug.Log("Any other platform"); #endif

Platform custom #defines

It is also possible to add to the built-in selection of #define directives by supplying your own. Open the Other Settings panel of the Player settings and navigate to the Scripting Define Symbols text box.

Enter the names of the symbols you want to define for that particular platform, separated by semicolons. These symbols can then be used as the conditions for #if directives, just like the built-in ones.

Global custom #defines

You can define your own preprocessor directives to control which code gets included when compiling. To do this you must add a text file with the extra directives to the AssetsAny media or data that can be used in your game or project. An asset may come from a file created outside of Unity, such as a 3D Model, an audio file or an image. You can also create some asset types in Unity, such as an Animator Controller, an Audio Mixer or a Render Texture. More info

See in Glossary folder. The name of the file depends on the language you are using. The extension is .rsp:

C# (player and editor scripts) <Project Path>/Assets/mcs.rsp

As an example, if you include the single line -define:UNITY_DEBUG in your mcs.rsp file, the #define directive UNITY_DEBUG exists as a global #define for C# scripts, except for Editor scripts.

Every time you make changes to .rsp files, you need to recompile in order for them to be effective. You can do this by updating or reimporting a single script (.js or .cs) file.

Note:__If you want to modify only global #define directives, use Scripting Define Symbols__ in Player settings, because this covers all the compilers. If you choose the .rsp files instead, you need to provide one file for every compiler Unity uses.

The use of .rsp files is described in the ‘Help’ section of the mcs application, which is included in the Editor installation folder. You can get more information by running mcs -help .

Note that the .rsp file needs to match the compiler being invoked. For example:

when targeting the .NET 3.5 Equivalent (deprecated) scripting runtime version, mcs is used with mcs.rsp , and

is used with , and when targeting the .NET 4.x Eqivalent scripting runtime version compiler, csc is used with csc.rsp .