CoreXLSX

Excel spreadsheet (XLSX) format parser written in pure Swift

CoreXLSX is a library focused on representing the low-level structure of the XML-based XLSX spreadsheet format. It allows you to open a spreadsheet archive with .xlsx extension and map its internal structure into model types expressed directly in Swift.

Important to note that this library provides read-only support only for the .xlsx format. As the older legacy .xls spreadsheet format has completely different internals, please refer to other libraries if you need to work with files of that type.

If your .xlsx files use ECMA-376 agile encryption (which seems to be the most popular variety), have a look at the CryptoOffice library.

Automatically generated documentation is available on our GitHub Pages.

Join our Discord for any questions and friendly banter.

Example

To run the example project, clone the repo, and run pod install from the Example directory first.

Model types in CoreXLSX directly map internal structure of XLSX format with more sensible naming applied to a few attributes. The API is pretty simple:

import CoreXLSX

let filepath = "./categories.xlsx"
guard let file = XLSXFile(filepath: filepath) else {
  fatalError("XLSX file at \(filepath) is corrupted or does not exist")
}

for wbk in try file.parseWorkbooks() {
  for (name, path) in try file.parseWorksheetPathsAndNames(workbook: wbk) {
    if let worksheetName = name {
      print("This worksheet has a name: \(worksheetName)")
    }

    let worksheet = try file.parseWorksheet(at: path)
    for row in worksheet.data?.rows ?? [] {
      for c in row.cells {
        print(c)
      }
    }
  }
}

This prints raw cell data from every worksheet in the given XLSX file. Please refer to the Worksheet model for more atttributes you might need to read from a parsed file.

Cell references

You should not address cells via their indices in the cells array. Every cell has a reference property, which you can read to understand where exactly a given cell is located. Corresponding properties on the CellReference struct give you the exact position of a cell.

Empty cells

The .xlsx format makes a clear distinction between an empty cell and absence of a cell. If you're not getting a cell or a row when iterating through the cells array, this means that there is no such cell or row in your document. Your .xlsx document should have empty cells and rows written in it in the first place for you to be able to read them.

Making this distinction makes the format more efficient, especially for sparse spreadsheets. If you had a spreadsheet with a single cell Z1000000, it wouldn't contain millions of empty cells and a single cell with a value. The file only stores a single cell, which allows sparse spreadsheets to be quickly saved and loaded, also taking less space on the filesystem.

Finding a cell by a cell reference

Given how the .xlsx format stores cells, you potentially have to iterate through all cells and build your own mapping from cell references to actual cell values. The CoreXLSX library does not currently do this automatically, and you will have to implement your own mapping if you need it. You're welcome to submit a pull request that adds such functionality as an optional step during parsing.

Shared strings

Strings in spreadsheet internals are frequently represented as strings shared between multiple worksheets. To parse a string value from a cell you should use stringValue(_: SharedStrings) function on Cell together with parseSharedString() on XLSXFile.

Here's how you can get all strings in column "C" for example:

if let sharedStrings = try file.parseSharedStrings() {
  let columnCStrings = worksheet.cells(atColumns: [ColumnReference("C")!])
    .compactMap { $0.stringValue(sharedStrings) }
}

To parse a date value from a cell, use dateValue property on the Cell type:

let columnCDates = worksheet.cells(atColumns: [ColumnReference("C")!])
  .compactMap { $0.dateValue }

Similarly, to parse rich strings, use the richStringValue function:

if let richStrings = try file.parseSharedStrings() {
  let columnCRichStrings = worksheet.cells(atColumns: [ColumnReference("C")!])
    .compactMap { $0.richStringValue(sharedStrings) }
}

Styles

Since version 0.5.0 you can parse style information from the archive with the new parseStyles() function. Please refer to the Styles model for more details. You should also note that not all XLSX files contain style information, so you should be prepared to handle the errors thrown from parseStyles() function in that case.

Here's a short example that fetches a list of fonts used:

let styles = try file.parseStyles()
let fonts = styles.fonts?.items.compactMap { $0.name?.value }

To get formatting for a given cell, use format(in:) and font(in:) functions, passing it the result of parseStyles:

let styles = try file.parseStyles()
let format = worksheet.data?.rows.first?.cells.first?.format(in: styles)
let font = worksheet.data?.rows.first?.cells.first?.font(in: styles)

Reporting compatibility issues

If you stumble upon a file that can't be parsed, please file an issue posting the exact error message. Thanks to use of standard Swift Codable protocol, detailed errors are generated listing a missing attribute, so it can be easily added to the model enabling broader format support. Attaching a file that can't be parsed would also greatly help in diagnosing issues. If these files contain any sensitive data, we suggest obfuscating or generating fake data with same tools that generated original files, assuming the issue can still be reproduced this way.

If the whole file can't be attached, try passing a sufficiently large value (between 10 and 20 usually works well) to errorContextLength argument of XLSXFile initializer. This will bundle the failing XML snippet with the debug description of thrown errors. Please also attach the full debug description if possible when reporting issues.

How does it work?

Since every XLSX file is a zip archive of XML files, CoreXLSX uses XMLCoder library and standard Codable protocols to map XML nodes and atrributes into plain Swift structs. ZIPFoundation is used for in-memory decompression of zip archives. A detailed description is available here.

Requirements

Apple Platforms

• Xcode 11.3 or later
• Swift 5.1 or later
• iOS 9.0 / watchOS 2.0 / tvOS 9.0 / macOS 10.11 or later deployment targets

Linux

• Ubuntu 16.04 or later
• Swift 5.1 or later

Installation

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 CoreXLSX as a dependency is as easy as adding it to the dependencies value of your Package.swift.

dependencies: [
  .package(url: "https://github.com/CoreOffice/CoreXLSX.git",
           .upToNextMinor(from: "0.14.1"))
]

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

CocoaPods

CoreXLSX is available through CocoaPods on Apple's platforms. To install it, simply add pod 'CoreXLSX', '~> 0.14.1' to your Podfile like shown here:

source 'https://github.com/CocoaPods/Specs.git'
# Uncomment the next line to define a global platform for your project
# platform :ios, '9.0'
use_frameworks!
target '<Your Target Name>' do
  pod 'CoreXLSX', '~> 0.14.1'
end

Contributing

Development Workflow

On macOS the easiest way to start working on the project is to open the Package.swift file in Xcode 11 or later. There is an extensive test suite that both tests files end-to-end and isolated snippets against their corresponding model values.

If you prefer not to work with Xcode, the project fully supports SwiftPM and the usual workflow with swift build and swift test should work, otherwise please report this as a bug.

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 inconsistent 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 coreoffice@desiatov.com.

License

CoreXLSX is available under the Apache 2.0 license. See the LICENSE file for more info.