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The official MongoDB driver for Swift applications on macOS and Linux.



The latest documentation is available here.

Bugs / Feature Requests

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

  1. Create an account and login:
  2. Navigate to the SWIFT project:
  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.


MongoSwift works with Swift 5.0+ on MacOS and Linux.

Installation is supported via Swift Package Manager.

Step 1: Install Required System Libraries (Linux Only)

The driver vendors and wraps the MongoDB C driver (libmongoc), which depends on a number of external C libraries when built in Linux environments. As a result, these libraries must be installed on your system in order to build MongoSwift.

To install those libraries, please follow the instructions from libmongoc's documentation.

Step 2: Install MongoSwift

The driver contains two modules to support a variety of use cases: an asynchronous API in MongoSwift, and a synchronous API in MongoSwiftSync. The modules share a BSON implementation and a number of core types such as options structs.

To install the driver, add the package and relevant module as a dependency in your project's Package.swift file:

// swift-tools-version:5.0
import PackageDescription

let package = Package(
    name: "MyPackage",
    dependencies: [
        .package(url: "", from: "VERSION.STRING.HERE"),
    targets: [
        // Async module
        .target(name: "MyAsyncTarget", dependencies: ["MongoSwift"]),
        // Sync module
        .target(name: "MySyncTarget", dependencies: ["MongoSwiftSync"])

Then run swift build to download, compile, and link all your dependencies.

Example Usage

Note: You should call cleanupMongoSwift() exactly once at the end of your application to release all memory and other resources allocated by libmongoc.

Connect to MongoDB and Create a Collection


import MongoSwift
import NIO

let elg = MultiThreadedEventLoopGroup(numberOfThreads: 4)
let client = try MongoClient("mongodb://localhost:27017", using: elg)

defer {
    // clean up driver resources

    // shut down EventLoopGroup
    try? elg.syncShutdownGracefully()

let db = client.db("myDB")
let result = db.createCollection("myCollection").flatMap { collection in
    // use collection...


import MongoSwiftSync

defer {
    // free driver resources

let client = try MongoClient("mongodb://localhost:27017")

let db = client.db("myDB")
let collection = try db.createCollection("myCollection")

// use collection...

Note: we have included the client connectionString parameter for clarity, but if connecting to the default "mongodb://localhost:27017"it may be omitted.

Create and Insert a Document


let doc: Document = ["_id": 100, "a": 1, "b": 2, "c": 3]
collection.insertOne(doc).whenSuccess { result in
    print(result?.insertedId ?? "") // prints `.int64(100)`


let doc: Document = ["_id": 100, "a": 1, "b": 2, "c": 3]
let result = try collection.insertOne(doc)
print(result?.insertedId ?? "") // prints `.int64(100)`

Find Documents


let query: Document = ["a": 1]
let result = collection.find(query).flatMap { cursor in
    cursor.forEach { doc in


let query: Document = ["a": 1]
let documents = try collection.find(query)
for d in documents {
    print(try d.get())

Work With and Modify Documents

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

print(doc) // prints `{"a" : 1, "b" : 2, "c" : 3}`
print(doc["a"] ?? "") // 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 = { 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 Document 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.

Usage With Kitura, Vapor, and Perfect

The Examples/ directory contains sample projects that use the driver with Kitura, Vapor, and Perfect.

Please note that the driver is built using SwiftNIO 2, and therefore is incompatible with frameworks built upon SwiftNIO 1. SwiftNIO 2 is used as of Vapor 4.0 and Kitura 2.5.

Development Instructions

See our development guide for instructions for building and testing the driver.

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