How to get export of .gdoc/.gslides in .pdf?

[kautaleksei]

In iOS sdk we have method for this: https://developers.google.com/drive/ios/devguide/files

Some files in Google Drive are not directly downloadable. Google Docs, Sheets, and Slides must be converted into a portable format. These files can be downloaded using the export URL. For example, to export a document as a PDF:

NSString *url = [NSString stringWithFormat:@"https://www.googleapis.com/drive/v3/files/%@/export?alt=media&mimeType=application/pdf",
                          file.identifier]

[kautaleksei]

I have found only this solution: http://stackoverflow.com/questions/32975533/google-drive-import-google-docs
but it's looks like a "hack". Can you add support for this, or point how I can do it in better way?
Thank you.