Categories on URL and Data to create a zip archive without any external dependencies

URL+Zip.swift

public extension URL {
  
  /// Creates a zip archive of the file/folder represented by this URL and returns a references to the zipped file
  ///
  /// - parameter dest: the destination URL; if nil, the destination will be this URL with ".zip" appended
  func zip(dest: URL? = nil) throws -> URL {
    let destURL = dest ?? self.appendingPathExtension("zip")
    
    let fm = FileManager.default
    var isDir: ObjCBool = false
    
    let srcDir: URL
    let srcDirIsTemporary: Bool
    if !self.path.isEmpty && self.isFileURL && fm.fileExists(atPath: path, isDirectory: &isDir) && isDir.boolValue == true {
      // this URL is a directory: just zip it in-place
      srcDir = self
      srcDirIsTemporary = false
    } else {
      // otherwise we need to copy the simple file to a temporary directory in order for
      // NSFileCoordinatorReadingOptions.ForUploading to actually zip it up
      srcDir = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(NSUUID().uuidString)
      try fm.createDirectory(at: srcDir, withIntermediateDirectories: true, attributes: nil)
      let tmpURL = srcDir.appendingPathComponent(self.lastPathComponent.isEmpty ? "file" : self.lastPathComponent)
      try fm.copyItem(at: self, to: tmpURL)
      srcDirIsTemporary = true
    }
    
    let coord = NSFileCoordinator()
    var preBlockError: NSError?
    var blockError: NSError?
    
    // coordinateReadingItemAtURL is invoked synchronously, but the passed in zippedURL is only valid
    // for the duration of the block, so it needs to be copied out
    coord.coordinate(readingItemAt: srcDir, options: NSFileCoordinator.ReadingOptions.forUploading, error: &preBlockError) { (zippedURL: URL) -> Void in
      do {
        try fm.copyItem(at: zippedURL, to: destURL)
      } catch let err {
        blockError = err as NSError
      }
    }
    
    if srcDirIsTemporary { try fm.removeItem(at: srcDir) }
    if let error = preBlockError ?? blockError { throw error }
    return destURL
  }
  
  /// Creates a zip archive of the file/folder represented by this URL and returns the zipped contents
  func zipToData() throws -> Data {
    let zipURL = try self.zip()
    let fm = FileManager.default
    let zippedData = try Data(contentsOf: zipURL, options: NSData.ReadingOptions())
    try fm.removeItem(at: zipURL) // clean up
    return zippedData
  }
}

public extension Data {
  /// Creates a zip archive of this data via a temporary file and returns the zipped contents
  func zip() throws -> Data {
    let tmpURL = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(NSUUID().uuidString)
    try self.write(to: tmpURL, options: NSData.WritingOptions.atomic)
    let zipURL = try tmpURL.zip()
    let fm = FileManager.default
    let zippedData = try Data(contentsOf: zipURL, options: NSData.ReadingOptions())
    try fm.removeItem(at: tmpURL) // clean up
    try fm.removeItem(at: zipURL)
    return zippedData
  }
}