Raise Hand using PubSub - iOS

Let us see how we can use PubSub to implement Raise Hand functionality. If you are not familiar with the PubSub mechanism and PubSub class, you can follow this guide.

Implementing Raise Hand

1. The first step is choosing the topic that all participants publish and subscribe to, so everyone knows when a participant raises their hand. We will be using RAISE_HAND as the topic for this one.
2. On the raiseHand button, publish any message to that specific topic.

Swift

extension RoomViewController {
  // Button that publishes the raise hand message when tapped
  @IBAction func raiseHandTapped(_ sender: Any) {
    Task {
      do {
        try await room?.pubSub.publish(topic: "RAISE_HAND", message: "Raise Hand")
      } catch {
        print("publish error: \(error)")
      }
    }
  }
}

3. Now let us subscribe to the RAISE_HAND topic after joining, and show an alert to all the participants showing who raised the hand.

Swift

extension RoomViewController: RoomEventListener {
    /// Room joined
    func onRoomJoined() {
      //...
      Task {
        do {
          try await room?.pubSub.subscribe(topic: "RAISE_HAND", listener: self)
        } catch {
          print("subscribe error: \(error)")
        }
      }
    }
}

extension RoomViewController: PubSubMessageListener {
    func onMessageReceived(_ message: PubSubMessage) {
        print("Message Received:= " + message.message)
        let localParticipantID = room?.localParticipant.id
        if(message.topic == "RAISE_HAND"){
            self.showToast(message: "\(message.senderId == localParticipantID ? "You" : "\(message.senderName)") raised hand 🖐🏼", font: .systemFont(ofSize: 18))
        }
    }
}

extension UIViewController {
  func showToast(message: String, font: UIFont) {
        let toastLabel = UILabel(frame: CGRect(x: self.view.frame.size.width/2 - 125, y: self.view.frame.size.height - 100, width: 250, height: 50))
        toastLabel.font = font
        toastLabel.textAlignment = .center;
        toastLabel.text = message
        self.view.addSubview(toastLabel)
        DispatchQueue.main.asyncAfter(deadline: .now() + 3.0) {
            toastLabel.removeFromSuperview()
        }
    }
} 

API Reference

The API references for all the methods and events utilised in this guide are provided below.

• PubSub