FileReader.swift

func open() -> Bool {
  guard channel == nil else { return true }
  guard let path = (fileURL.path as NSString).utf8String else { return false }
  channel = DispatchIO(type: .random, path: path, oflag: 0, mode: 0, queue: .main, cleanupHandler: { error in
    print("Closed a channel with status: \(error)")
  })
  // Load the whole requested byte range at once
  channel?.setLimit(lowWater: .max)
  guard self.channel != nil else { return false }
  print("Opened a channel at \(fileURL)")
  return true
}
func close() {
  channel?.close()
  channel = nil
}