Simple function to add an entire folder to a ZipArchive. Uses getSubPathName to avoid recreating whole disk structure. Uses iterators, no recursion.

gistfile1.php

<?php

function addFolderToZip(\ZipArchive $zip, $dir) {
        
    $iterator = new \RecursiveIteratorIterator(
        new \RecursiveDirectoryIterator($dir, \RecursiveDirectoryIterator::SKIP_DOTS),
        \RecursiveIteratorIterator::SELF_FIRST);
    
    $zip->addEmptyDir(basename($dir));
    
    foreach ($iterator as $item) {
        if ($item->isDir()) {
            $zip->addEmptyDir(basename($dir) . DIRECTORY_SEPARATOR . $iterator->getSubPathName());
        } else {
            $zip->addFile($item->getPathname(), basename($dir) . DIRECTORY_SEPARATOR . $iterator->getSubPathName());
        }
    }
    
}