iOS相当于Android外部/公共存储(iOS equivalent of Android external/public storage)

 要提供文件以供下载，请创建一个读取文件的php脚本，然后使用正确的标头提供它 
 
// ensure the file exists
if(isset($_GET['file']) && file_exists($_GET['file'])){

  // Read the file some.zip
  $file = file_get_contents($_GET['file']);

  // Set headers to serve the file for download
  header('Content-Type: application/zip');
  header('Content-Disposition: attachment; filename="$_GET['file']"'); // name file here
  header('Content-Length: ' . strlen($file)); // length of the file

  // echo the file
  echo $file;
}

To serve a file for download, create a php script that reads the file, then serves it with the proper headers
 
// ensure the file exists
if(isset($_GET['file']) && file_exists($_GET['file'])){

  // Read the file some.zip
  $file = file_get_contents($_GET['file']);

  // Set headers to serve the file for download
  header('Content-Type: application/zip');
  header('Content-Disposition: attachment; filename="$_GET['file']"'); // name file here
  header('Content-Length: ' . strlen($file)); // length of the file

  // echo the file
  echo $file;
}