Persistent Participant States (Peer Metadata)

Metadata can be set initially in the HMSConfig object that's passed into the join method.

This section will show you how to:

1. Read Peer Metadata.
2. Respond to when a remote peer changes its metadata.
3. How to set a peer's metadata.

The HMSPeer object prior to 0.2.1 contained customerDescription a read-only string whose value wouldn't change throughout a call. This has been replaced with metadata. The value is initially assigned as before but now can be changed by the peer who owns it.

Any peer can change the metadata for themselves. Currently one peer cannot change another peer's metadata.

To change their own metadata value the peer should call change(metadata:completion:) on their HMSSSDK instance.

The data may be any arbitrary string.

Reading metadata

To read metadata, read the metadata value on any HMSPeer instance.

Responding to updates

Whenever a remote peer's metadata is updated a callback will be received in on(peer: HMSPeer, update: HMSPeerUpdate) of HMSUpdateListener where the update value will be of type HMSPeerUpdate.metadataUpdated.

When this callback is received the UI for that peer should be updated as well.

Updating Metadata

Here is how a peer can set their own metadata to a random string. In this case the string is stringified json.

let newMetadata = "{\"ms\": 100 }"
hmsSdk.change(metadata: newMetadata) { success, error in
   ...
}

How to Attach Objects/Information to a Participant object in the Meeting so that All Participants can Access it

Peer Model instance exposes a shared dictionary called metadata. You can use this to store any objects or primitives and they will get attached to that peer. And will be available to all participants in the room. You store key value pairs to this dictionary like following.

For example let's see how to attach a link to Particiapnt's Avatar image in Metadata of the Participant so that Everyone in the Meeting can show the Avatar for that Participant.

roomModel.localPeerModel?.metadata["Avatar Image URL"] = /* url string to avatar image */

How would other Participants access this attached Avatar on a Peer and show it with their Video Tile?

// Render video of each peer in the call
ForEach(roomModel.peerModels) { peerModel in
    VStack {
        if let urlString = peerModel.metadata["Avatar Image URL"] as? String, let url = URL(string: urlString) {
            AsyncImage(url: url)
        }
        HMSVideoTrackView(peer: peerModel)
            .frame(height: 200)
    }
}

Note that metadata dictionary is Published property of peer model, thus any changes in this dictionary values reflect in your SwiftUI views automatically.