let url = "https://www.googleapis.com/drive/v3/files/(identifier)?alt=media"

service.fetchObject(
    with: URL(string: url)!,
    delegate: self,
    didFinish: #selector(GoogleDriveFileListTableViewController.downloadWithTicket(ticket:finishedWithObject:error:))
)

// Parse results and display
func downloadWithTicket(ticket : GTLServiceTicket, finishedWithObject response : GTLDriveFileList, error : NSError?) {
    if let error = error {
        showAlert(title: "Error", message: error.localizedDescription)
        return
    }

}