pure Swift BSON library

What's New

SwiftBSON v3.1.0


The MongoDB Swift driver team is pleased to announce the 3.1.0 release of SwiftBSON.

With this release, the library now officially supports use on iOS versions 13+.

Included Tickets

New Feature

  • [SWIFT-1301] - Add a new BSON Binary subtype 7
  • [SWIFT-1500] - Set the minimum supported iOS version for the SwiftBSON library to iOS 13

A full list of tickets included in this release can be found here.

Swift BSON


The official MongoDB BSON implementation in Swift!


Bugs / Feature Requests

Think you've found a bug? Want to see a new feature in swift-bson? Please open a case in our issue management tool, JIRA:

  1. Create an account and login: jira.mongodb.org
  2. Navigate to the SWIFT project: jira.mongodb.org/browse/SWIFT
  3. Click Create Issue - Please provide as much information as possible about the issue and how to reproduce it.

Bug reports in JIRA for all driver projects (i.e. NODE, PYTHON, CSHARP, JAVA) and the Core Server (i.e. SERVER) project are public.


The library supports use with Swift 5.1+. The minimum macOS version required to build the library is 10.14. The library is tested in continuous integration against macOS 10.14, Ubuntu 16.04, and Ubuntu 18.04.

Installation is supported via Swift Package Manager.

Install BSON

To install the library, add the package as a dependency in your project's Package.swift file:

// swift-tools-version:5.1
import PackageDescription

let package = Package(
    name: "MyPackage",
    dependencies: [
        .package(url: "https://github.com/mongodb/swift-bson", .upToNextMajor(from: "3.1.0"))
    targets: [
        .target(name: "MyTarget", dependencies: ["SwiftBSON"])

Example Usage

Work With and Modify Documents

import SwiftBSON

var doc: BSONDocument = ["a": 1, "b": 2, "c": 3]

print(doc) // prints `{"a" : 1, "b" : 2, "c" : 3}`
print(doc["a", default: "Not Found!"]) // prints `.int64(1)`

// Set a new value
doc["d"] = 4
print(doc) // prints `{"a" : 1, "b" : 2, "c" : 3, "d" : 4}`

// Using functional methods like map, filter:
let evensDoc = doc.filter { elem in
    guard let value = elem.value.asInt() else {
        return false
    return value % 2 == 0
print(evensDoc) // prints `{ "b" : 2, "d" : 4 }`

let doubled = doc.map { elem -> Int in
    guard case let value = .int64(value) else {
        return 0

    return Int(value * 2)
print(doubled) // prints `[2, 4, 6, 8]`

Note that BSONDocument conforms to Collection, so useful methods from Sequence and Collection are all available. However, runtime guarantees are not yet met for many of these methods.

Development Instructions

See our development guide for the MongoDB driver to get started. To run the tests for the BSON library you can make use of the Makefile and run: make test-pretty (uses xcpretty to change the output format) or just make test (for environments without ruby).


This repository previously contained Swift bindings for libbson, the MongoDB C driver's BSON library. Those bindings are still available under the 2.1.0 tag. Major version 3.0 and up will be used for the BSON library.


  • Swift Tools 5.1.0
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Last updated: Wed Feb 01 2023 11:52:52 GMT-0500 (GMT-05:00)