The Multipeer Connectivity Framework is a powerful tool that opens up the world of communication between devices, allowing data to be exchanged and shared seamlessly. This comprehensive tutorial is tailored for those looking to tap into this potential, guiding you through the process of creating a fully-functional chat application. This application serves as a conduit for users to exchange messages in real-time. For a successful implementation, ensure that an iOS device is readily available, alongside the iOS Simulator, to facilitate thorough testing and a holistic experience. This tutorial is crafted with precision, utilizing Xcode 10 and targeting iOS 12 for optimal performance.

Unlocking the Potential of Multipeer Connectivity: A Comprehensive Guide to Building a Chat Application

Kickstarting Your Project with Xcode:

  1. Launch Xcode and initiate a new project by selecting ‘Single View App’;
  2. When prompted for a product name, input ‘IOSMultipeerConnectivityTutorial’. This name serves as a unique identifier for your project;
  3. Ensure that your Organization Name and Organization Identifier are filled out with the appropriate values, tailoring the setup to your personal or organizational branding;
  4. Set ‘Swift’ as the programming language to leverage its modern syntax and features;
  5. Click ‘Next’ to proceed to the next stage of the setup.

Configuring the User Interface:

  1. Navigate to the Storyboard and select the ‘View Controller’;
  2. Access the ‘Editor’ menu, choose ‘Embed in’, and select ‘Navigation Controller’ to enhance navigational capabilities;
  3. Focus on the main view within the ViewController, and adjust the background color to Light Gray via the Attributes inspector for a visually pleasing aesthetic;
  4. Incorporate a Text View from the Object Library to the main view, ensuring it is configured to display chat messages. Remember to clear any placeholder text and disable the ‘Editable’ option to ensure it serves solely as an output medium;
  5. Below the Text View, introduce a Text Field, which will be the input field for chat messages;
  6. Add a ‘Send’ button below the Text Field. This button plays a dual role: triggering the message sending process and updating the Text View with the new message;
  7. To ensure a seamless layout, use the ‘Resolve Auto Layout Issues’ button, opting for ‘Reset to Suggested Constraints’.

Connecting the Interface to Code:

Open the Assistant Editor, ensuring that ViewController.swift is visible and accessible.

Establish connections between your UI elements and the Swift file:

  1. Create an Outlet for the Text View;
  2. Create an Outlet for the Text Field;
  3. Create an Action for the ‘Send’ button, which will house the logic for message sending and display.

Incorporating Multipeer Connectivity:

  1. Import the MultipeerConnectivity framework to your ViewController.swift file to unlock connectivity features;
  2. Conform your ViewController class to the MCSessionDelegate and MCBrowserViewControllerDelegate protocols, preparing it to handle session management and browser delegation;
  3. Define essential properties for session management and message handling;
  4. peerID: Uniquely identifies a user within a session;
  5. mcSession: Manages and maintains the multipeer connectivity session;
  6. mcAdvertiserAssistant: Advertises sessions to nearby devices and manages incoming invitations;
  7. messageToSend: A string that temporarily holds the message to be sent.

Enhancing the ViewDidLoad Method:

Transform the viewDidLoad() method into a powerhouse of initial setup and configuration, ensuring that the foundational elements of the application are meticulously established:

override func viewDidLoad() {

  // Configuring the Navigation Bar:
  // A share button is integrated into the navigation bar for seamless user interaction, paving the way for connectivity options.
  navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .action, target: self, action: #selector(showConnectionMenu))

  // Establishing the Multipeer Session:
  // The device’s name is ingeniously utilized as the unique identifier (peerID) for the multipeer session, ensuring a personalized touch.
  peerID = MCPeerID(displayName:
  mcSession = MCSession(peer: peerID, securityIdentity: nil, encryptionPreference: .required)
  mcSession.delegate = self

Diving Deeper:

  • The navigationItem.rightBarButtonItem: This line of code gracefully positions a button on the navigation bar, ensuring that the connection menu is just a tap away;
  • The MCPeerID and MCSession: These crucial lines of code not only establish the unique identifier for the session but also configure the session with a stringent requirement for encryption, showcasing a commitment to user security.

Building the Connection Menu:

Cultivate a user-friendly interface to manage connections with the showConnectionMenu() method:

@objc func showConnectionMenu() {
  let ac = UIAlertController(title: "Connection Menu", message: nil, preferredStyle: .actionSheet)
  ac.addAction(UIAlertAction(title: "Host a session", style: .default, handler: hostSession))
  ac.addAction(UIAlertAction(title: "Join a session", style: .default, handler: joinSession))
  ac.addAction(UIAlertAction(title: "Cancel", style: .cancel))
  present(ac, animated: true)

Strategic Insights:

  • User Empowerment: Users are presented with clear options, empowering them to either initiate a new session or join an existing one, fostering a sense of control and engagement;
  • Sleek Design: The action sheet presentation style ensures a sleek and intuitive user experience.

Facilitating Session Connectivity:

Transform the way users connect with the hostSession(action:) and joinSession(action:) methods:

// Hosting a New Session:

func hostSession(action: UIAlertAction) {

  mcAdvertiserAssistant = MCAdvertiserAssistant(serviceType: "ioscreator-chat", discoveryInfo: nil, session: mcSession)



// Joining an Existing Session:

func joinSession(action: UIAlertAction) {

  let mcBrowser = MCBrowserViewController(serviceType: "ioscreator-chat", session: mcSession)

  mcBrowser.delegate = self

  present(mcBrowser, animated: true)


Valuable Takeaways:

  • Unique Service Type: The ioscreator-chat serves as a unique identifier, ensuring that devices can accurately pinpoint and connect to the desired session;
  • Engagement with Nearby Devices: The MCBrowserViewController not only finds but also flawlessly presents nearby devices, facilitating seamless session invitations.

Mastering Message Sending:

Elevate the user experience with a robust message-sending functionality:

@IBAction func tapSendButton(_ sender: Any) {
  // Constructing the Message:
  messageToSend = "\(peerID.displayName): \(inputMessage.text!)\n"
  if let message = .utf8, allowLossyConversion: false) {
    do {
      // Sending the Message:
      try mcSession.send(message, toPeers: mcSession.connectedPeers, with: .unreliable)
      chatView.text += messageToSend
      inputMessage.text = ""
    } catch {
      // Handle any errors gracefully:
      print("Error encountered while sending the message.")

Key Highlights:

  • Data Conversion: The message is meticulously converted into a Data object, ensuring compatibility and seamless transmission;
  • Error Handling: Potential errors are handled with care, providing feedback and ensuring the application remains robust;
  • User Feedback: Upon successful message sending, the chat view is updated and the input field is cleared, providing instant feedback to the user.

Integrating Delegate Methods for Seamless Connectivity

In order to ensure a seamless and interactive user experience, implementing the delegate methods for both MCSessionDelegate and MCBrowserViewControllerDelegate protocols becomes crucial. These methods play a pivotal role in handling session state changes, data reception, and user interactions with the browser view controller.

1. Monitoring Session State Changes:

Enhance user awareness and debugging capabilities by meticulously monitoring the changes in session states and providing real-time console outputs:

func session(_ session: MCSession, peer peerID: MCPeerID, didChange state: MCSessionState) {
  switch state {
  case .connected:
    // When a peer is successfully connected:
    print("Successfully connected to: \(peerID.displayName)")
  case .connecting:
    // When a connection attempt is in progress:
    print("Attempting to connect to: \(peerID.displayName)")
  case .notConnected:
    // When a peer is disconnected or connection fails:
    print("Disconnected from: \(peerID.displayName)")
  @unknown default:
    // Handling unforeseen cases gracefully:
    fatalError("An unexpected state has occurred in the MCSession.")
  • Proactive Monitoring: This method enables the application to actively monitor the connection status with peers, ensuring any state changes are instantly recognized and logged;
  • Debugging Aid: By logging these state changes, developers are provided with a powerful tool for debugging and optimizing connectivity issues.

2. Receiving and Displaying Messages:

Ensure a dynamic and responsive chat environment by efficiently handling incoming messages and updating the chat view in real-time:

func session(_ session: MCSession, didReceive data: Data, fromPeer peerID: MCPeerID) {
  DispatchQueue.main.async { [weak self] in
    if let strongSelf = self {
      // Converting the received data to a string:
      let receivedMessage = String(data: data, encoding: .utf8) ?? ""
      // Updating the chat view with the new message:
      strongSelf.chatView.text += receivedMessage
  • Main Thread Utilization: Ensuring all UI updates are performed on the main thread to maintain a smooth and responsive user experience;
  • Safe Unwrapping: Utilizing optional binding to safeguard against nil values and potential crashes.

3. Handling Browser View Controller Interactions:

Facilitate a user-friendly experience when interacting with the browser view controller, ensuring it dismisses gracefully whether the session is established or cancelled:

func browserViewControllerDidFinish(_ browserViewController: MCBrowserViewController) {
  // Dismissing the browser view controller upon session establishment:
  browserViewController.dismiss(animated: true)

func browserViewControllerWasCancelled(_ browserViewController: MCBrowserViewController) {
  // Dismissing the browser view controller when the user cancels the action:
  browserViewController.dismiss(animated: true)
  • Streamlined User Experience: Providing a consistent and intuitive flow, regardless of whether the user chooses to connect or cancel;
  • Animation for Visual Continuity: Utilizing animations for dismissing the browser ensures a smooth transition back to the main interface.

Building and Testing the Application:

With all components and delegate methods in place, it’s time to bring the application to life:

  • Launching the Application: Build and run the project using Xcode, ensuring to test on both the iOS simulator and a physical iOS device to cover different usage scenarios. Unlock new possibilities in UI with swiftui scrollview!;
  • Initiating a Session: Utilize the share icon within the application to host a session on one device and subsequently join the session from another;
  • Engaging in Chat: Enter a message into the text field, and observe as the message is seamlessly transmitted and displayed on the chat views of all connected peers;
  • Cross-Device Communication: Verify that messages are successfully exchanged between the simulator and the iOS device, ensuring robust connectivity;
  • Real-Time Updates: Pay attention to the chat view updates, confirming that messages are promptly displayed, enhancing the chat experience.


In the comprehensive journey of creating a chat application using the Multipeer Connectivity framework in iOS, we’ve delved deep into the intricacies of setting up a robust and interactive environment. From the initial steps of crafting the user interface in Xcode, to implementing the essential functionalities and delegate methods, this tutorial has covered extensive ground to ensure developers are well-equipped to build their own peer-to-peer communication applications.

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