属性	方法
UNITY_EDITOR	#define directive for calling 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_STANDALONE	#define directive for compiling/executing code for any standalone platform (Mac OS X, Windows or Linux).
UNITY_STANDALONE_WIN	#define directive for compiling/executing code specifically for Windows standalone applications.
UNITY_STANDALONE_OSX	#define directive for compiling/executing code specifically for Mac OS X (including Universal, PPC and Intel architectures).
UNITY_STANDALONE_LINUX	#define directive for compiling/executing code specifically for Linux standalone applications.
UNITY_ANDROID	#define directive for the Android platform.
UNITY_IOS	#define directive for compiling/executing code for the iOS platform.
UNITY_IPHONE	Deprecated. Use UNITY_IOS instead.
UNITY_WEBGL	#define directive for WebGL.
UNITY_WP_8_1	#define directive for Windows Phone 8.1.
UNITY_PS4	#define directive for running PlayStation 4 code.
UNITY_XBOXONE	#define directive for executing Xbox One code.
UNITY_WII	#define directive for compiling/executing code for the Wii console.
UNITY_SAMSUNGTV	#define directive for executing Samsung TV code.

样例：

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

public class PlatformDefines : MonoBehaviour {

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

}

// 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
}

Unity宏定义官方文档