CopyFilesBuildPostProcessor.cs

using UnityEngine;
using UnityEditor;
using UnityEditor.Callbacks;
using System;
using System.IO;
 
public static class CopyFilesBuildPostProcessor
{
    private const string PathToCopy = "PathToFiles";

    [PostProcessBuild]
    public static void OnPostProcessBuild(BuildTarget target, string pathToBuiltProject)
    {
        // Copy all files from the Unity Assets/{PathToCopy} directory to a directory
        // called {PathToCopy} under the build's output directory.
        var sourceFullPath = Path.Combine(Application.dataPath, PathToCopy);
        var destinationFullPath = Path.Combine(pathToBuiltProject, PathToCopy);
        CopyFiles(sourceFullPath, destinationFullPath);
    }

    private static void CopyFiles(string source, string destination)
    {
        var files = Directory.GetFiles(source);
        foreach (var sourceFile in files)
        {
            // Get just the filename for the file, so we can determine whether the file
            // exists in the destination.
            var filename = Path.GetFileName(sourceFile);
            var destinationFile = Path.Combine(destination, filename);
            var exists = File.Exists(destinationFile);
            var doCopy = !exists; // If the file doesn't exist, we definitely need to copy it!

            if (exists)
            {
                // If the file exists at the destination and the source has been modified more
                // recently than the destination file, we will copy the source file again.
                var sourceTimestamp = File.GetLastWriteTime(sourceFile);
                var destinationTimestamp = File.GetLastWriteTime(destinationFile);
                doCopy = sourceTimestamp > destinationTimestamp;
            }

            if (doCopy)
            {
                try
                {
                    File.Copy(sourceFile, destinationFile);
                }
                catch (Exception e)
                {
                    Debug.Log("Failed to copy file: " + e.Message);
                }
            }
        }
    }
}