Vonage API Developer

Swift

Handle Video Stats

In this step you implement OTSubscriberKitNetworkStatsDelegate to diagnose stuttering and surface network health in your app.

What you'll monitor	How it is delivered	How it can be used
`videoPacketsLost` / `videoBytesReceived`	Periodic — `videoNetworkStatsUpdated`	Confirm the receive path is struggling (stutter, freezes)
`transport` (local downlink bandwidth)	Periodic — `mediaLinkStatsUpdated`	Suggest “Your connection looks weak”
`remotePublisherTransport` (remote uplink)	Periodic — `mediaLinkStatsUpdated`	Suggest “The other participant’s network may be unstable”
`networkDegradationSource`	Periodic and on change	Pick local vs remote messaging
Significant network change	Event — `networkConditionChanged`	Banners, toasts, support logs

iOS-specific: Periodic stats and network condition events are methods on the same OTSubscriberKitNetworkStatsDelegate—not a separate listener type.

Adopt the delegate in an extension:

extension VonageVideoManager: OTSubscriberKitNetworkStatsDelegate {
    // ...
}

1. Handle Subscriber Video Stats

func subscriber(_ subscriber: OTSubscriberKit, videoNetworkStatsUpdated stats: OTSubscriberKitVideoNetworkStats) {
    print("videoBytesReceived=\(stats.videoBytesReceived)")
    print("videoPacketsLost=\(stats.videoPacketsLost)")
    print("videoPacketsReceived=\(stats.videoPacketsReceived)")

    DispatchQueue.main.async {
        self.latestObservabilityStats = ObservabilityStats.fromVideoStats(
            stats,
            mediaLink: self.latestMediaLinkSnapshot
        )
    }
}

Callbacks may arrive off the main queue. Update @Published overlay state on the main queue.

2. Handle Periodic Media Link Stats

func subscriber(_ subscriber: OTSubscriberKit, mediaLinkStatsUpdated mediaLinkStats: OTSubscriberKitMediaLinkStats) {
    applyMediaLinkStats(mediaLinkStats)
}

3. Handle Network Condition Events

Implement subscriber(_:networkConditionChanged:reason:) for significant changes—see Network condition:

func subscriber(
    _ subscriber: OTSubscriberKit,
    networkConditionChanged mediaLinkStats: OTSubscriberKitMediaLinkStats,
    reason: OTNetworkReason
) {
    print("networkConditionChanged reason=\(reason.rawValue)")
    applyMediaLinkStats(mediaLinkStats, networkConditionChangeReason: reason)
    handleNetworkDegradation(mediaLinkStats)
}

Shared merge helper:

private func applyMediaLinkStats(
    _ mediaLinkStats: OTSubscriberKitMediaLinkStats,
    networkConditionChangeReason: OTNetworkReason? = nil
) {
    let localBandwidth = mediaLinkStats.transport?.connectionEstimatedBandwidth
    let remoteBandwidth = mediaLinkStats.remotePublisherTransport?.connectionEstimatedBandwidth
    let localCondition = mediaLinkStats.transport?.networkCondition
    let remoteCondition = mediaLinkStats.remotePublisherTransport?.networkCondition

    DispatchQueue.main.async {
        self.latestMediaLinkSnapshot = MediaLinkSnapshot(
            localEstimatedBandwidth: localBandwidth,
            remoteEstimatedBandwidth: remoteBandwidth,
            networkDegradationSource: mediaLinkStats.networkDegradationSource,
            localNetworkCondition: localCondition,
            remoteNetworkCondition: remoteCondition,
            lastNetworkConditionChangeReason: networkConditionChangeReason
        )
        if var current = self.latestObservabilityStats {
            current.merge(mediaLink: self.latestMediaLinkSnapshot)
            self.latestObservabilityStats = current
        }
    }
}

4. React to Degradation on Network Condition Events

private func handleNetworkDegradation(_ mediaLinkStats: OTSubscriberKitMediaLinkStats) {
    let localCondition = mediaLinkStats.transport?.networkCondition ?? .unknown
    let remoteCondition = mediaLinkStats.remotePublisherTransport?.networkCondition ?? .unknown

    switch mediaLinkStats.networkDegradationSource {
    case .local:
        print("Local network degraded (condition=\(localCondition.rawValue))")
        // e.g. show: "Your connection looks weak"
    case .remote:
        print("Remote publisher network degraded (condition=\(remoteCondition.rawValue))")
        // e.g. show: "The other participant's network may be unstable"
    case .bothOrUnclear:
        print("Degradation unclear — local=\(localCondition.rawValue) remote=\(remoteCondition.rawValue)")
    default:
        break
    }
}

Define ObservabilityStats, MediaLinkSnapshot, and helpers in your project (mirror the Android sample’s model). If remotePublisherTransport stays nil, confirm the remote publisher used settings.senderStatsTrack = true.

Next: Pass merged stats into SwiftUI and render the overlay.