title: UIDocumentPickerViewController in import mode returns .icloud files
body: <p>using a <code>UIDocumentPickerViewController</code> in <code>.import</code> mode on iCloud Drive sometimes returns files with a <code>.icloud</code> extension. This extension means that the file are not physically present on the device, but on iCloud.</p>
  
  <p>Since the mode is <code>.import</code>, the files returned by 
  <code>documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentsAt urls: [URL])</code>
  are a copy of the actual files.
  Therefore, it becomes impossible to call <code>startDownloadingUbiquitousItemAtURL</code> on <code>NSFileManager</code>.</p>
  
  <p>One precision that might (maybe) be important: this happens when the user selects a directory in the <code>startDownloadingUbiquitousItemAtURL</code>. In the callback I then perform <code>FileManager.default.enumerator(at: urls[0], includingPropertiesForKeys: nil)</code> which returns the list of files inside the directory. Some of those files unfortunately are sometimes .icloud files, not the actual files.</p>
  
  <p>Somehow, I can't find a workaround to access those files, any idea ?</p>
  
  <p>Thanks !</p>