Unity sample assets cross platform initialise editor script

using UnityEngine;
using UnityEditor;
using System.Collections.Generic;

[InitializeOnLoad]
public class CrossPlatformInitialize {

    // Custom compiler defines:
    //
    // CROSS_PLATFORM_INPUT : denotes that cross platform input package exists, so that other packages can use their CrossPlatformInput functions.
    // EDITOR_MOBILE_INPUT : denotes that mobile input should be used in editor, if a mobile build target is selected. (i.e. using Unity Remote app).
    // MOBILE_INPUT : denotes that mobile input should be used right now!

    static CrossPlatformInitialize()
    {
        var defines = GetDefinesList(buildTargetGroups[0]);
        if (!defines.Contains("CROSS_PLATFORM_INPUT"))
        {
            SetEnabled("CROSS_PLATFORM_INPUT",true,false);
            SetEnabled("MOBILE_INPUT",true,true);
        }
    }

    [MenuItem("Mobile Input/Enable")]
    static void Enable()
    {

        SetEnabled("MOBILE_INPUT",true,true);
        switch (EditorUserBuildSettings.activeBuildTarget)
        {
            case BuildTarget.Android:
            case BuildTarget.iPhone:
            case BuildTarget.WP8Player:
            case BuildTarget.BlackBerry:
            EditorUtility.DisplayDialog("Mobile Input","You have enabled Mobile Input. You'll need to use the Unity Remote app on a connected device to control your game in the Editor.","OK");
            break;

        default:
            EditorUtility.DisplayDialog("Mobile Input","You have enabled Mobile Input, but you have a non-mobile build target selected in your build settings. The mobile control rigs won't be active or visible on-screen until you switch the build target to a mobile platform.","OK");
            break;
        }
    }

    [MenuItem("Mobile Input/Enable", true)]
    static bool EnableValidate()
    {
        var defines = GetDefinesList(mobileBuildTargetGroups[0]);
        return !defines.Contains("MOBILE_INPUT");
    }

    [MenuItem("Mobile Input/Disable")]
    static void Disable()
    {
        SetEnabled("MOBILE_INPUT",false,true);
        switch (EditorUserBuildSettings.activeBuildTarget)
        {
        case BuildTarget.Android:
        case BuildTarget.iPhone:
        case BuildTarget.WP8Player:
        case BuildTarget.BlackBerry:
            EditorUtility.DisplayDialog("Mobile Input","You have disabled Mobile Input. Mobile control rigs won't be visible, and the Cross Platform Input functions will always return standalone controls.","OK");
            break;
        }


    }
    [MenuItem("Mobile Input/Disable", true)]
    static bool DisableValidate()
    {
        var defines = GetDefinesList(mobileBuildTargetGroups[0]);
        return defines.Contains("MOBILE_INPUT");
    }

    static BuildTargetGroup[] buildTargetGroups = new BuildTargetGroup[]
    {
        BuildTargetGroup.Standalone,
        BuildTargetGroup.WebPlayer,
        BuildTargetGroup.Android,
        BuildTargetGroup.iPhone,
        BuildTargetGroup.WP8,
        BuildTargetGroup.BlackBerry,
    };

    static BuildTargetGroup[] mobileBuildTargetGroups = new BuildTargetGroup[]
    {
        BuildTargetGroup.Android,
        BuildTargetGroup.iPhone,
        BuildTargetGroup.WP8,
        BuildTargetGroup.BlackBerry,
    };

    static void SetEnabled(string defineName, bool enable, bool mobile)
    {
        //Debug.Log("setting "+defineName+" to "+enable);
        foreach (var group in mobile ? mobileBuildTargetGroups : buildTargetGroups)
        {
            var defines = GetDefinesList(group);
            if (enable)
            {
                if (!defines.Contains(defineName))
                {
                    defines.Add(defineName);
                } else {
                    return;
                }
            } else  {
                if (defines.Contains(defineName))
                {
                    while (defines.Contains(defineName)) defines.Remove(defineName);
                } else {
                    return;
                }
            }
            string definesString = string.Join(";",defines.ToArray());
            PlayerSettings.SetScriptingDefineSymbolsForGroup( group, definesString );
        }
    }

    static List<string> GetDefinesList(BuildTargetGroup group)
    {
        return new List<string>( PlayerSettings.GetScriptingDefineSymbolsForGroup( group ).Split(';'));
    }


}