Add user consent to an existing React Native app built with XMTP

Managing user consent is essential for enhancing privacy and the user experience. Providing user consent features in your app gives your users better control over who can send them messages.

If you already have an XMTP app, integrating universal allow/block features becomes crucial. This guide walks you through adding consent logic to your app.

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Installation Steps

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Prerequisites

• Node.js
• npm or Yarn
• React Native CLI
• Xcode (for iOS)

1. Initialize React Native Project

If you haven't already created a React Native project, start by initializing one:

npx react-native init xmtprn

2. Install Expo Modules

Install the latest Expo modules:

npx install-expo-modules@latest

3. Install XMTP React Native SDK

Install the XMTP React Native SDK using npm:

yarn install @xmtp/react-native-sdk

4. Update Podfile for iOS

Update the Podfile to set the minimum iOS platform. Open the Podfile in your iOS directory and modify the platform line:

platform :ios, '16.0'

5. Update Xcode Target

Ensure your Xcode project's target is updated to iOS 16.0 or higher.

6. Add Babel Plugin

Install the Babel plugin required for the XMTP SDK:

npm add @babel/plugin-proposal-export-namespace-from

7. Configure Babel

Update your Babel configuration. Open your babel.config.js and add the plugin:

module.exports = {
  presets: ["module:@react-native/babel-preset"],
  plugins: ["@babel/plugin-proposal-export-namespace-from"],
};

8. Install iOS Pods

Navigate to the iOS directory and install the necessary pods:

cd ios && pod install && cd ..

9. Start the Application

Finally, start your React Native application:

npm run ios

Tutorial

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Initialize XMTP Client with Consent

Here's your existing initXmtpWithKeys function, updated to include the consent refresh logic.

const initXmtpWithKeys = async function () {
  // ... previous code
  const xmtp = await Client.create(wallet);
  // Refresh the consent list to make sure your application is up-to-date with the network
  await xmtp.contacts.refreshConsentList();
};

Filtering conversations based on consent

Using the consentState property of the conversation object, you can filter the conversations based on consent.

const allowed = await Promise.all(
  conversations.map(async (conversation) => {
    const consentState = await conversation.consentState();
    return consentState === "allowed" ? conversation : null;
  }),
).then((results) => results.filter(Boolean));

const requests = await Promise.all(
  filteredConversations.map(async (conversation) => {
    const consentState = await conversation.consentState();
    return consentState === "unknown" || consentState === "denied"
      ? conversation
      : null;
  }),
).then((results) => results.filter(Boolean));

Request inbox

You can now create a separate inbox for requests. This inbox will only show the conversations that have not been allowed yet.

{
  activeTab === "requests" ? (
    <TouchableOpacity
      style={styles.conversationListItem}
      onPress={() => setActiveTabWithStorage("allowed")}>
      <Text style={styles.conversationName}>← Allowed</Text>
    </TouchableOpacity>
  ) : (
    <TouchableOpacity
      style={styles.conversationListItem}
      onPress={() => setActiveTabWithStorage("requests")}>
      <Text style={styles.conversationName}>Requests →</Text>
    </TouchableOpacity>
  );
}

Refresh consent when opening a conversation

To ensure that your application respects the latest user consent preferences, it's important to refresh the consent state every time a conversation is opened. This can be done by calling the refreshConsentList method of the XMTP client before any interaction within a conversation occurs.

// Function to select and open a conversation
const openConversation = async (conversation) => {
  // Refresh the consent list to make sure your application is up-to-date with the network
  await client.contacts.refreshConsentList();
  // Now it's safe to open the conversation
  setSelectedConversation(conversation);
};

Allow and denied actions

Every time you open a conversation on the request tab you can show a popup with the allow and deny actions. You can use the consentState property of the conversation object to show the popup only when the consent state is unknown.

// Inside your MessageContainer component
const [showPopup, setShowPopup] = useState(
  conversation.consentState === "unknown",
);

// Function to handle the acceptance of a contact
const handleAccept = async () => {
  // Refresh the consent list first
  await client.contacts.refreshConsentList();
  // Allow the contact
  await client.contacts.allow([conversation.peerAddress]);
  // Hide the popup
  setShowPopup(false);
  // Refresh the consent list
  await client.contacts.refreshConsentList();
  // Log the acceptance
  console.log("accepted", conversation.peerAddress);
};

// Function to handle the blocking of a contact
const handleBlock = async () => {
  // Refresh the consent list first
  await client.contacts.refreshConsentList();
  // Block the contact
  await client.contacts.deny([conversation.peerAddress]);
  // Hide the popup
  setShowPopup(false);
  // Refresh the consent list
  await client.contacts.refreshConsentList();
  // Log the blocking
  console.log("denied", conversation.peerAddress);
};

Updating consent on message send

A user's response to the conversation is considered consent. Previously to send a message we need to ensure the consent state is correctly set to "allowed".

const handleSendMessage = async (newMessage) => {
  if (!newMessage.trim()) {
    alert("Empty message");
    return;
  }
  if (conversation && conversation.peerAddress) {
    // Refresh the consent list to ensure it's up-to-date
    await client.contacts.refreshConsentList();
    // Update the consent state to "allowed"
    await client.contacts.allow([conversation.peerAddress]);
    // Send the message
    await conversation.send(newMessage);
  } else if (conversation) {
    // Handle creating a new conversation and sending a message
    // The SDK handles newConversation as Allowed
    // ...
  }
};

Include this step in your message sending workflow to maintain proper consent practices within your XMTP application.

Troubleshooting

Resolving Buffer Issues with Ethers.js

Ethers.js relies on the Buffer class, which is a global object in Node.js but not available in the React Native environment. To resolve this, you need to polyfill Buffer.

1. Install the Buffer Package:

   If you haven't already, install the buffer package using npm:

   npm install buffer

2. Polyfill Buffer:

   In the entry point of your application, such as index.js, add Buffer to the global scope:

   global.Buffer = global.Buffer || require("buffer").Buffer;

Always synchronize consent states: Before updating consent preferences on the network, ensure you refresh the consent list with await xmtp.contacts.refreshConsentList();. Update the network's consent list only in these scenarios:

• User Denies Contact: Set to denied if a user blocks or unsubscribes.
• User Allows Contact: Set to allowed if a user subscribes or enables notifications.
• Legacy Preferences: Align the network with any existing local preferences.
• User Response: Set to allowed if the user has engaged in conversation.