FileMon

FileMon.swift

class FileMon {
  static let queue = DispatchQueue(label: "FileMon")
  
  let path: String
  let file: Int32
  let source: DispatchSourceFileSystemObject
  
  deinit {
    source.cancel()
  }
  
  init(_ path: String, handler: @escaping () -> Void) {
    self.path = path
    file = open(path, O_EVTONLY)
    source = DispatchSource.makeFileSystemObjectSource(fileDescriptor: file, eventMask: .write, queue: FileMon.queue)
    source.setEventHandler(handler: handler)
    source.setCancelHandler { [file] in
      close(file)
    }
    source.resume()
  }
}