AutomaticBuildFromClass.cs

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

public class AutomaticBuild : EditorWindow
{
 	const string BUILD_PATH = "Builds";

	[MenuItem("Tools/Build Game &d")]
	private static void OpenWindow()
	{
		EditorWindow.GetWindow<AutomaticBuild>(true, "Automated Build", true).Show();
	}

	BuildOptions options = BuildOptions.None;

	void OnGUI()
	{
		bool developmentBuild = options == BuildOptions.Development;
		developmentBuild = EditorGUILayout.Toggle("Development", developmentBuild);
		options = developmentBuild ? BuildOptions.Development : BuildOptions.None;


		GUILayout.FlexibleSpace();

		if(GUILayout.Button("Build"))
		{
			Rect r = this.position;
			r.x += 10f;
			this.position = r;
			EditorApplication.delayCall += () => { DoBuild(); };
		}
	}

	void DoBuild()
	{
		int previousBuildNumber = EditorPrefs.GetInt("AutomatedBuildIncrement", 0);
		int currentBuildNumber = previousBuildNumber + 1;
		EditorPrefs.SetInt("AutomatedBuildIncrement", currentBuildNumber);

		CreateFolderIfItDoesntExist(BUILD_PATH);
		string[] scenes = GetScenesInProject();

		Debug.Log( string.Join("\n", scenes) );

		string result = BuildPipeline.BuildPlayer(
			scenes,
			string.Format("{0}/MyBuild-{1}", BUILD_PATH, currentBuildNumber),
			BuildTarget.StandaloneOSXIntel,
			options);

		if( string.IsNullOrEmpty(result) )
			Debug.Log("Build success!");
		else
			Debug.Log(result);
	}

	private static void CreateFolderIfItDoesntExist(string path)
	{
		if( !Directory.Exists(path) )
		{
			Debug.Log("Created directory: " + Path.GetFullPath(path));
			Directory.CreateDirectory(path);
		}
	}

	private static string[] GetScenesInProject()
	{
		return Directory.GetFiles(
			"Assets",
			"*.unity",
			SearchOption.AllDirectories);
	}
}