FileReader.swift

let fileURL = Bundle.main.url(forResource: "DataFile", withExtension: nil)!
let reader = FileReader(fileURL: fileURL)
if reader.open() {
  reader.read(byteRange: 0..<20) { data in
    if let data = data {
      print("Read bytes: \(data.map({ UInt8($0) }))")
    }
    else {
      print("Failed to read data")
    }
  }
}
else {
  print("Failed to open")
}