Swift support for Microsoft OLE2 (also known as Structured Storage or Compound File Binary Format)

What's New



This release fixes an issue with file size attributes in some cases (such as iOS Document-based App with SwiftUI)
during OLEFile creation.

Merged pull requests:


Swift support for Microsoft OLE2 format, also known as Structured Storage, Compound File Binary Format or Compound Document File Format.

Some of the file formats that utilize it:

  • Encrypted Office Open XML documents (Microsoft Office 2003+, Word .docx, Excel .xlsx, PowerPoint .pptx)
  • Microsoft Office 97-2003 documents (BIFF5 and later in Word .doc, Excel .xls, PowerPoint .ppt, Visio .vsd, Project .mpp)
  • vbaProject.bin in MS Office 2007+ files
  • Image Composer and FlashPix files
  • Outlook messages
  • StickyNotes
  • Zeiss AxioVision ZVI files
  • Olympus FluoView OIB files
  • McAfee antivirus quarantine files
  • Hancom Word's .hwp file format

...and more. If you know of a file format that is based on CFBF, please submit a pull request so that it's added to the list.

Automatically generated documentation is available on our GitHub Pages.


An OLE2 file has a minuature filesystem embedded in it that is represented as a tree of DirectoryEntry values in OLEKit.

To read a file and an entry within the file:

  1. Add import OLEKit at the top of a relevant source file.
  2. Use OLEFile(_ path: String) to create a new instance with a path to your OLE2 file.
  3. Use the root property of type DirectoryEntry on OLEFile to read the root directory entry, and the children property on DirectoryEntry to traverse the tree of entries.
  4. Call stream(_ entry:) on your OLEFile instance to get access to the entry. This returns an instance of DataReader that provides helper read() functions for reading raw data.
import OLEKit

let filepath = "./categories.xlsx"
let entryName = "EncryptionInfo"

let ole = try OLEFile(filepath)
  let infoEntry = oleFile.root.children.first(where: { $0.name == entryName })
else { fatalError("entry \(entryName) not found in file \(filepath)") }

let stream = try oleFile.stream(infoEntry)

// Read version bytes from the encryption stream in little-endian order
let major: UInt16 = stream.read()
let minor: UInt16 = stream.read()

guard major == 4 && minor == 4
else { fatalError("unknown version: major \(major), minor \(minor)") }

// change position in the `stream`
reader.seek(toOffset: 8)
// get the rest of the data
let rawStreamData = reader.readDataToEnd()

You can refer to source code of the CryptoOffice library for a more detailed example.


Apple Platforms

  • Xcode 11.2 or later
  • Swift 5.1 or later


  • Swift 5.1 or later


Swift Package Manager

Swift Package Manager is a tool for managing the distribution of Swift code. It’s integrated with the Swift build system to automate the process of downloading, compiling, and linking dependencies on all platforms.

Once you have your Swift package set up, adding OLEKit as a dependency is as easy as adding it to the dependencies value of your Package.swift.

dependencies: [
    url: "https://github.com/CoreOffice/OLEKit.git",
    .upToNextMinor(from: "0.2.0")

If you're using OLEKit in an app built with Xcode, you can also add it as a direct dependency using Xcode's GUI.



If this library saved you any amount of time or money, please consider sponsoring the work of its maintainer. While some of the sponsorship tiers give you priority support or even consulting time, any amount is appreciated and helps in maintaining the project.

Coding Style

This project uses SwiftFormat and SwiftLint to enforce formatting and coding style. We encourage you to run SwiftFormat within a local clone of the repository in whatever way works best for you either manually or automatically via an Xcode extension, build phase or git pre-commit hook etc.

To guarantee that these tools run before you commit your changes on macOS, you're encouraged to run this once to set up the pre-commit hook:

brew bundle # installs SwiftLint, SwiftFormat and pre-commit
pre-commit install # installs pre-commit hook to run checks before you commit

Refer to the pre-commit documentation page for more details and installation instructions for other platforms.

SwiftFormat and SwiftLint also run on CI for every PR and thus a CI build can fail with incosistent formatting or style. We require CI builds to pass for all PRs before merging.

Code of Conduct

This project adheres to the Contributor Covenant Code of Conduct. By participating, you are expected to uphold this code. Please report unacceptable behavior to conduct@coreoffice.org.


OLEKit is licensed under the Apache License, Version 2.0 (the "License"); you may not use this library except in compliance with the License. See the LICENSE file for more info.

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

OLEKit is based on the code from the olefile library, which uses FreeBSD-style license, check out LICENSE-olefile for details.


  • Swift Tools 5.1.0
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Last updated: Mon Jan 30 2023 02:21:40 GMT-0500 (GMT-05:00)