Platform Dependent Compilation

Unity includes a feature named "Platform Dependent Compilation". This consists of some preprocessor directives that let you partition your scripts to compile and execute a section of code exclusively for one of the supported platforms.

Furthermore, you can run this code within the Editor, so you can compile the code specifically for your mobile/console and test it in the Editor!

Platform Defines

The platform defines that Unity supports for your scripts are:

UNITY_EDITORDefine for calling Unity Editor scripts from your game code.
UNITY_STANDALONE_OSXPlatform define for compiling/executing code specifically for Mac OS (This includes Universal, PPC and Intel architectures).
UNITY_DASHBOARD_WIDGETPlatform define when creating code for Mac OS dashboard widgets.
UNITY_STANDALONE_WINUse this when you want to compile/execute code for Windows stand alone applications.
UNITY_STANDALONE_LINUXUse this when you want to compile/execute code for Linux stand alone applications.
UNITY_STANDALONEUse this to compile/execute code for any standalone platform (Mac, Windows or Linux).
UNITY_WEBPLAYERPlatform define for web player content (this includes Windows and Mac Web player executables).
UNITY_WIIPlatform define for compiling/executing code for the Wii console.
UNITY_IPHONEPlatform define for compiling/executing code for the iPhone platform.
UNITY_ANDROIDPlatform define for the Android platform.
UNITY_PS3Platform define for running PlayStation 3 code.
UNITY_XBOX360Platform define for executing Xbox 360 code.
UNITY_NACLPlatform define when compiling code for Google native client (this will be set additionally to UNITY_WEBPLAYER).
UNITY_FLASHPlatform define when compiling code for Adobe Flash.
UNITY_BLACKBERRYPlatform define for a Blackberry10 device.
UNITY_WP8Platform define for Windows Phone 8.
UNITY_METROPlatform define for Windows Store Apps (additionally NETFX_CORE is defined when compiling C# files against .NET Core).
UNITY_WINRTEquivalent to UNITY_WP8 | UNITY_METRO

Also you can compile code selectively depending on the version of the engine you are working on. Currently the supported ones are:

UNITY_2_6Platform define for the major version of Unity 2.6.
UNITY_2_6_1Platform define for specific version 1 from the major release 2.6.
UNITY_3_0Platform define for the major version of Unity 3.0.
UNITY_3_0_0Platform define for the specific version 0 of Unity 3.0.
UNITY_3_1Platform define for major version of Unity 3.1.
UNITY_3_2Platform define for major version of Unity 3.2.
UNITY_3_3Platform define for major version of Unity 3.3.
UNITY_3_4Platform define for major version of Unity 3.4.
UNITY_3_5Platform define for major version of Unity 3.5.
UNITY_4_0Platform define for major version of Unity 4.0.
UNITY_4_0_1Platform define for major version of Unity 4.0.1.
UNITY_4_1Platform define for major version of Unity 4.1.
UNITY_4_2Platform define for major version of Unity 4.2.

Note: For versions before 2.6.0 there are no platform defines as this feature was first introduced in that version.

Testing precompiled code.

We are going to show a small example of how to use the precompiled code. This will simply print a message that depends on the platform you have selected to build your target.

First of all, select the platform you want to test your code against by clicking on File -> Build Settings. This will bring the build settings window to select your target platform.


Build Settings window with the WebPlayer Selected as Target platform.

Select the platform you want to test your precompiled code against and press the Switch Editor button to tell Unity which platform you are targeting.

Create a script and copy/paste this code:-

// JS
function Awake() {
  #if UNITY_EDITOR
    Debug.Log("Unity Editor");
  #endif

  #if UNITY_IPHONE
    Debug.Log("Iphone");
  #endif

  #if UNITY_STANDALONE_OSX
    Debug.Log("Stand Alone OSX");
  #endif

  #if UNITY_STANDALONE_WIN
    Debug.Log("Stand Alone Windows");
  #endif	
}


// C#
using UnityEngine;
using System.Collections;

public class PlatformDefines : MonoBehaviour {
  void Start () {

    #if UNITY_EDITOR
      Debug.Log("Unity Editor");
    #endif

    #if UNITY_IPHONE
      Debug.Log("Iphone");
    #endif

    #if UNITY_STANDALONE_OSX
	Debug.Log("Stand Alone OSX");
    #endif

    #if UNITY_STANDALONE_WIN
      Debug.Log("Stand Alone Windows");
    #endif

  }			   
}


// Boo
import UnityEngine

class PlatformDefines (MonoBehaviour): 

	def Start ():
		ifdef UNITY_EDITOR:
			Debug.Log("Unity Editor")

		ifdef UNITY_IPHONE:
			Debug.Log("IPhone")

		ifdef UNITY_STANDALONE_OSX:
			Debug.Log("Stand Alone OSX")

		ifdef not UNITY_IPHONE:
			Debug.Log("not an iPhone")

Then, depending on which platform you selected, one of the messages will get printed on the Unity console when you press play.

Note that in c# you can use a CONDITIONAL attribute which is a more clean, less error-prone way of stripping out functions, see http://msdn.microsoft.com/en-us/library/4xssyw96.aspx.

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

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

However, Boo currently supports only the ifdef directive.

Platform Custom Defines

It is also possible to add to the built-in selection of defines by supplying your own. In the Other Settings panel of the Player Settings, you will see the Scripting Define Symbols textbox.

Here, you can 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 "Assets/" folder. The name of the file depends on the language you are using, and the extension is .rsp:

C#<Project Path>/Assets/smcs.rsp
C# - Editor Scripts<Project Path>/Assets/gmcs.rsp
UnityScript<Project Path>/Assets/us.rsp
Boo<Project Path>/Assets/boo.rsp

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

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

If you want to modify only global defines, you should use Scripting Define Symbols in Player Settings, because this will cover all the compilers. If you choose the .rsp files instead, you'll have to provide one file for every compiler Unity uses, and you won't know when one or another compiler is used.

The use of the .rsp files is described in the help section of the smcs application which is included in the Editor installation folder. You can get more information by running "smcs -help". Also, bear in mind the .rsp file needs to match the compiler being invoked. For example, when targeting the web player, smcs is used with smcs.rsp; when targeting standalone players, gmcs is used with gmcs.rsp; when targeting MS compiler, csc is used with csc.rsp; and so on.

Page last updated: 2013-12-04