#if的作用是指导编译器针对不同的情况分别编译。例如：
#ifUNITY_ANDROID Debug.Log("Android"); #endif #if UNITY_IPHONE Debug.Log("IOS"); #endif
众所周知，Unity跨平台非常的多，下面是所有平台的关键字
| UNITY_EDITOR | Define for calling Unity Editor scripts from your game code. |
| UNITY_STANDALONE_OSX | Platform define for compiling/executing code specifically for Mac OS (This includes Universal, PPC and Intel architectures). |
| UNITY_DASHBOARD_WIDGET | Platform define when creating code for Mac OS dashboard widgets. |
| UNITY_STANDALONE_WIN | Use this when you want to compile/execute code for Windows stand alone applications. |
| UNITY_STANDALONE_LINUX | Use this when you want to compile/execute code for Linux stand alone applications. |
| UNITY_STANDALONE | Use this to compile/execute code for any standalone platform (Mac, Windows or Linux). |
| UNITY_WEBPLAYER | Platform define for web player content (this includes Windows and Mac Web player executables). |
| UNITY_WII | Platform define for compiling/executing code for the Wii console. |
| UNITY_IPHONE | Platform define for compiling/executing code for the iPhone platform. |
| UNITY_ANDROID | Platform define for the Android platform. |
| UNITY_PS3 | Platform define for running PlayStation 3 code. |
| UNITY_XBOX360 | Platform define for executing Xbox 360 code. |
| UNITY_NACL | Platform define when compiling code for Google native client (this will be set additionally to UNITY_WEBPLAYER). |
| UNITY_FLASH | Platform define when compiling code for Adobe Flash. |
| UNITY_BLACKBERRY | Platform define for a Blackberry10 device. |
| UNITY_WP8 | Platform define for Windows Phone 8. |
| UNITY_METRO | Platform define for Windows Store Apps (additionally NETFX_CORE is defined when compiling C# files against .NET Core). |