Swiftpack.co - Package - agisboye/SwiftLMDB


SwiftLMDB is an opinionated wrapper around the LMDB key/value database.

The wrapper abstracts away the C API and some of its concepts. Instead you get a clean Swift API that makes it easy to store arbitrary values in a fast and embedded database.

The only requirement is that keys and values can be converted to Data. To assert this, keys and values must conform to the DataConvertible protocol. Fundamental Swift value types are supported out of the box.


  • [x] Small and lightweight
  • [x] Fast
  • [x] Unit tested
  • [x] Xcode documentation
  • [x] Cross platform

SwiftLMDB has been tested on iOS and macOS, however it should also run on Linux. Feel free to test it out.


  • iOS 8.0+ or macOS 10.10+
  • Swift 5.0+


Swift Package Manager

Add SwiftLMDB as a dependency in your Package.swift file.

dependencies: [
.package(url: "https://github.com/agisboye/SwiftLMDB.git", from: "2.0.0")


To integrate LMDB into your Xcode project using Carthage, specify it in your Cartfile:

github "agisboye/SwiftLMDB"

Run carthage update to build the framework and drag SwiftLMDB.framework into your Xcode project.


Start by importing the module.

import SwiftLMDB

Creating a database

Databases are contained within an environment. An environment may contain multiple databases, each identified by their name.

let environment: Environment
let database: Database

do {
    // The folder in which the environment is opened must already exist.
    try FileManager.default.createDirectory(at: envURL, withIntermediateDirectories: true, attributes: nil)

    environment = try Environment(path: envURL.path, flags: [], maxDBs: 32)
    database = try environment.openDatabase(named: "db1", flags: [.create])

} catch {

Put a value

Any value conforming to DataConvertible can be inserted with any key conforming to DataConvertible.

try database.put(value: "Hello world!", forKey: "key1")

Get a value

When you need to get back a value from the database, you specify the expected type (the type of the value you put in) and the key. This returns an optional of the type that you specify.

if let value = try database.get(type: String.self, forKey: "key1") { // String?
    // String

Delete a value

try database.deleteValue(forKey: "key1")

Check if a key exists

try database.exists(key: "key1") // Bool


Removes all entries from the database.

try database.empty()

database.count == 0 // true


Removes all entries from the database and deletes the database from the environment. The database can no longer be used after calling this method and should be discarded.

try database.drop()


Contributions are very welcome. Open an issue or submit a pull request.


SwiftLMDB is available under the MIT license. See the LICENSE file for more info. LMDB is licensen under the OpenLDAP Public License.


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2.0.0 - Aug 29, 2019

This release brings the library up to date with the latest LMDB release (0.9.24). It also bumps the Swift version to 5 and updates the Package.swift manifest so that the library can be installed using Swift Package Manager.

The API has been cleaned up a little bit (mostly naming).

1.1.1 - Jan 24, 2018

Breaking changes:

  • The URL conformance to DataConvertible has been removed because the required initializer is only available on macOS 10.11+. There is no convenient way of changing the deployment target in the package manifest. If you rely on URL conforming to DataConvertible, and your deployment target is macOS 10.11+, you can implement the conformance yourself in an extension. See the implementation here.

1.1.0 - Sep 9, 2017

  • Changes the way various types are persisted to make them implementation agnostic as well as make the databases portable across systems of different endianess (#13). Thanks to @regexident.

Breaking changes: Certain types including numbers, Bool, Date are stored differently in this version, making it incompatible with databases created with previous versions of the library.