xmtp-ios provides a Swift implementation of an XMTP message API client for use with iOS apps.

Use xmtp-ios to build with XMTP to send messages between blockchain accounts, including DMs, notifications, announcements, and more.

This SDK is in Developer Preview status and ready for you to start building.

However, we do not recommend using Developer Preview software in production apps. Software in this status may change based on feedback.

Specifically, this SDK is missing this functionality:

• Specifying apiUrl, keyStoreType, codecs, maxContentSize, and appVersion when creating a Client
• Streaming all messages from all conversations

Follow along in the tracking issue for updates.

To learn more about XMTP and get answers to frequently asked questions, see FAQ about XMTP.

For a basic demonstration of the core concepts and capabilities of the xmtp-ios client SDK, see the Example app project.

Use Xcode to add to the project (File > Add Packages…) or add this to your Package.swift file:

.package(url: "https://github.com/xmtp/xmtp-ios", branch: "main")

The XMTP message API revolves around a message API client (client) that allows retrieving and sending messages to other XMTP network participants. A client must connect to a wallet app on startup. If this is the very first time the client is created, the client will generate a key bundle that is used to encrypt and authenticate messages. The key bundle persists encrypted in the network using an account signature. The public side of the key bundle is also regularly advertised on the network to allow parties to establish shared encryption keys. All of this happens transparently, without requiring any additional code.

import XMTP

// You'll want to replace this with a wallet from your application.
let account = try PrivateKey.generate()

// Create the client with your wallet. This will connect to the XMTP `dev` network by default.
// The account is anything that conforms to the `XMTP.SigningKey` protocol.
let client = try await Client.create(account: account)

// Start a conversation with XMTP
let conversation = try await client.conversations.newConversation(with: "0x3F11b27F323b62B159D2642964fa27C46C841897")

// Load all messages in the conversation
let messages = try await conversation.messages()
// Send a message
try await conversation.send(content: "gm")
// Listen for new messages in the conversation
for try await message in conversation.streamMessages() {
  print("\(message.senderAddress): \(message.body)")
}

A client is created with Client.create(account: SigningKey) async throws -> Client that requires passing in an object capable of creating signatures on your behalf. The client will request a signature in two cases:

1. To sign the newly generated key bundle. This happens only the very first time when a key bundle is not found in storage.
2. To sign a random salt used to encrypt the key bundle in storage. This happens every time the client is started, including the very first time).

Important: The client connects to the XMTP dev environment by default. Use ClientOptions to change this and other parameters of the network connection.

import XMTP

// Create the client with a `SigningKey` from your app
let client = try await Client.create(account: account, options: .init(api: .init(env: .production)))

You can save your keys from the client via the privateKeyBundle property:

// Create the client with a `SigningKey` from your app
let client = try await Client.create(account: account, options: .init(api: .init(env: .production)))

// Get the key bundle
let keys = client.privateKeyBundle

// Serialize the key bundle and store it somewhere safe
let keysData = try keys.serializedData()

Once you have those keys, you can create a new client with Client.from:

let keys = try PrivateKeyBundle(serializedData: keysData)
let client = try Client.from(bundle: keys, options: .init(api: .init(env: .production)))

You can configure the client's network connection and key storage method with these optional parameters of Client.create:

// Configure the client to use the `production` network
let clientOptions = ClientOptions(api: .init(env: .production))
let client = try await Client.create(account: account, options: clientOptions)

Note: The apiUrl, keyStoreType, codecs, maxContentSize and appVersion parameters from the XMTP client SDK for JavaScript (xmtp-js) are not yet supported.

Most of the time, when interacting with the network, you'll want to do it through conversations. Conversations are between two accounts.

import XMTP
// Create the client with a wallet from your app
let client = try await Client.create(account: account)
let conversations = try await client.conversations.list()

You can get a list of all conversations that have had one or more messages exchanged in the last 30 days.

let allConversations = try await client.conversations.list()

for conversation in allConversations {
  print("Saying GM to \(conversation.peerAddress)")
  try await conversation.send(content: "gm")
}

You can also listen for new conversations being started in real-time. This will allow apps to display incoming messages from new contacts.

Warning: This stream will continue infinitely. To end the stream, break from the loop.

for try await conversation in client.conversations.stream() {
  print("New conversation started with \(conversation.peerAddress)")

  // Say hello to your new friend
  try await conversation.send(content: "Hi there!")

  // Break from the loop to stop listening
  break
}

You can create a new conversation with any Ethereum address on the XMTP network.

let newConversation = try await client.conversations.newConversation(with: "0x3F11b27F323b62B159D2642964fa27C46C841897")

To be able to send a message, the recipient must have already created a client at least once and consequently advertised their key bundle on the network. Messages are addressed using account addresses. The message payload must be a plain string.

Note: Other types of content are currently not supported.

let conversation = try await client.conversations.newConversation(with: "0x3F11b27F323b62B159D2642964fa27C46C841897")
try await conversation.send(content: "Hello world")

You can receive the complete message history in a conversation by calling conversation.messages()

for conversation in client.conversations.list() {
  let messagesInConversation = try await conversation.messages()
}

It may be helpful to retrieve and process the messages in a conversation page by page. You can do this by calling conversation.messages(limit: Int, before: Date) which will return the specified number of messages sent before that time.

let conversation = try await client.conversations.newConversation(with: "0x3F11b27F323b62B159D2642964fa27C46C841897")

let messages = try await conversation.messages(limit: 25)
let nextPage = try await conversation.messages(limit: 25, before: messages[0].sent)

You can listen for any new messages (incoming or outgoing) in a conversation by calling conversation.streamMessages().

A successfully received message (that makes it through the decoding and decryption without throwing) can be trusted to be authentic. Authentic means that it was sent by the owner of the message.senderAddress account and that it wasn't modified in transit. The message.sent timestamp can be trusted to have been set by the sender.

The stream returned by the stream methods is an asynchronous iterator and as such is usable by a for-await-of loop. Note however that it is by its nature infinite, so any looping construct used with it will not terminate, unless the termination is explicitly initiated (by breaking the loop).

let conversation = try await client.conversations.newConversation(with: "0x3F11b27F323b62B159D2642964fa27C46C841897")

for try await message in conversation.streamMessages() {
  if message.senderAddress == client.address {
    // This message was sent from me
    continue
  }

  print("New message from \(message.senderAddress): \(message.body)")
}

Note: This package does not currently include the streamAllMessages() functionality from the XMTP client SDK for JavaScript (xmtp-js).

With XMTP, you can have multiple ongoing conversations with the same blockchain address. For example, you might want to have a conversation scoped to your particular app, or even a conversation scoped to a particular item in your app.

To accomplish this, you can pass a context with a conversationId when you are creating a conversation. We recommend conversation IDs start with a domain, to help avoid unwanted collisions between your app and other apps on the XMTP network.

// Start a scoped conversation with ID mydomain.xyz/foo
let conversation1 = try await client.conversations.newConversation(
  with: "0x3F11b27F323b62B159D2642964fa27C46C841897",
  context: .init(conversationID: "mydomain.xyz/foo")
)

// Start a scoped conversation with ID mydomain.xyz/bar. And add some metadata
let conversation2 = try await client.conversations.newConversation(
  with: "0x3F11b27F323b62B159D2642964fa27C46C841897",
  context: .init(conversationID: "mydomain.xyz/bar", metadata: ["title": "Bar conversation"])
)

// Get all the conversations
let conversations = try await client.conversations.list()

// Filter for the ones from your app
let myAppConversations = conversations.filter {
  guard let conversationID = $0.context?.conversationID else {
    return false
  }

  return conversationID.hasPrefix("mydomain.xyz/")
}

You can decode a single Envelope from XMTP using the decode method:

let conversation = try await client.conversations.newConversation(with: "0x3F11b27F323b62B159D2642964fa27C46C841897")

// Assume this function returns an Envelope that contains a message for the above conversation
let envelope = getEnvelopeFromXMTP()

let decodedMessage = try conversation.decode(envelope)

You can save a conversation object locally using its encodedContainer property. This returns a ConversationContainer object which conforms to Codable.

// Get a conversation
let conversation = try await client.conversations.newConversation(with: "0x3F11b27F323b62B159D2642964fa27C46C841897")

// Get a container.
let container = conversation.encodedContainer

// Dump it to JSON
let encoder = JSONEncoder()
let data = try encoder.encode(container)

// Get it back from JSON
let decoder = JSONDecoder()
let containerAgain = try decoder.decode(ConversationContainer.self, from: data)

// Get an actual Conversation object like we had above
let decodedConversation = containerAgain.decode(with: client)
try await decodedConversation.send(text: "hi")

All the send functions support SendOptions as an optional parameter. The contentType option allows specifying different types of content than the default simple string, which is identified with content type identifier ContentTypeText. Support for other types of content can be added by registering additional ContentCodecs with the Client. Every codec is associated with a content type identifier, ContentTypeId, which is used to signal to the Client which codec should be used to process the content that is being sent or received. See XIP-5 for more details on codecs and content types.

Codecs and content types may be proposed as interoperable standards through XRCs. If there is a concern that the recipient may not be able to handle a non-standard content type, the sender can use the contentFallback option to provide a string that describes the content being sent. If the recipient fails to decode the original content, the fallback will replace it and can be used to inform the recipient what the original content was.

// Assuming we've loaded a fictional NumberCodec that can be used to encode numbers,
// and is identified with ContentTypeNumber, we can use it as follows.
Client.register(codec: NumberCodec())

try await aliceConversation.send(content: 3.14, options: .init(contentType: ContentTypeNumber, contentFallback: "sending you a pie"))

Message content can be optionally compressed using the compression option. The value of the option is the name of the compression algorithm to use. Currently supported are gzip and deflate. Compression is applied to the bytes produced by the content codec.

Content will be decompressed transparently on the receiving end. Note that Client enforces maximum content size. The default limit can be overridden through the ClientOptions. Consequently a message that would expand beyond that limit on the receiving end will fail to decode.

try await conversation.send(text: '#'.repeat(1000), options: .init(compression: .gzip))

Because xmtp-ios is in active development, you should expect breaking revisions that might require you to adopt the latest SDK release to enable your app to continue working as expected.

XMTP communicates about breaking revisions in the XMTP Discord community, providing as much advance notice as possible. Additionally, breaking revisions in an xmtp-ios release are described on the Releases page.

Older versions of the SDK will eventually be deprecated, which means:

1. The network will not support and eventually actively reject connections from clients using deprecated versions.
2. Bugs will not be fixed in deprecated versions.

The following table provides the deprecation schedule.

Bug reports, feature requests, and PRs are welcome in accordance with these contribution guidelines.

XMTP provides both production and dev network environments to support the development phases of your project.

The production and dev networks are completely separate and not interchangeable. For example, for a given blockchain account, its XMTP identity on dev network is completely distinct from its XMTP identity on the production network, as are the messages associated with these identities. In addition, XMTP identities and messages created on the dev network can't be accessed from or moved to the production network, and vice versa.

Important: When you create a client, it connects to the XMTP dev environment by default. To learn how to use the env parameter to set your client's network environment, see Configure the client.

The env parameter accepts one of three valid values: dev, production, or local. Here are some best practices for when to use each environment:

• dev: Use to have a client communicate with the dev network. As a best practice, set env to dev while developing and testing your app. Follow this best practice to isolate test messages to dev inboxes.

• production: Use to have a client communicate with the production network. As a best practice, set env to production when your app is serving real users. Follow this best practice to isolate messages between real-world users to production inboxes.

• local: Use to have a client communicate with an XMTP node you are running locally. For example, an XMTP node developer can set env to local to generate client traffic to test a node running locally.

The production network is configured to store messages indefinitely. XMTP may occasionally delete messages and keys from the dev network, and will provide advance notice in the XMTP Discord community.