Delete all files inside of a directory.

deleteAllFilesInsideDirectory.php

  /**
   * Delete all content inside of given directory.
   *
   * @param string $folder
   *   Directory.
   */
  public function deleteAllFilesInsideDirectory(string $folder): void {
    $files = new \RecursiveIteratorIterator(
      new \RecursiveDirectoryIterator($folder, \FilesystemIterator::SKIP_DOTS),
      \RecursiveIteratorIterator::CHILD_FIRST
    );

    foreach ($files as $fileinfo) {
      if ($fileinfo->isDir()) {
        rmdir($fileinfo->getRealPath());
      }
      else {
        unlink($fileinfo->getRealPath());
      }
    }
  }