Vonage API Developer

Swift

Overview

Subscribe to a remote stream and assign networkStatsDelegate so you receive statistics callbacks. On iOS, video, audio, and media link stats (including network condition events) are delivered through a single OTSubscriberKitNetworkStatsDelegate—not separate listener objects like on Android.

The callback handling is implemented in the next step.

When a remote stream is created, build an OTSubscriber, set delegates, and subscribe:

func session(_ session: OTSession, streamCreated stream: OTStream) {
    guard subscriber == nil else { return }

    let subscriber = OTSubscriber(stream: stream, delegate: self)
    subscriber.networkStatsDelegate = self   // OTSubscriberKitNetworkStatsDelegate
    self.subscriber = subscriber

    var error: OTError?
    session.subscribe(subscriber, error: &error)
    if let error {
        print("Subscribe error: \(error)")
    }
}

Delegate	What it delivers
`OTSubscriberDelegate`	Connection lifecycle, subscriber view
`OTSubscriberKitNetworkStatsDelegate`	Video/audio stats, media link stats, network condition events

iOS-specific: Set networkStatsDelegate on the subscriber instance. There is no separate “media link listener” registration—implement mediaLinkStatsUpdated and networkConditionChanged on the same delegate type.

2. Clear State When the Stream Ends

Reset observability state when the stream is destroyed:

func session(_ session: OTSession, streamDestroyed stream: OTStream) {
    subscriber = nil
    latestObservabilityStats = nil
    latestMediaLinkSnapshot = nil
    DispatchQueue.main.async {
        self.subView = nil
    }
}

In subscriberDidConnect, assign the subscriber view for SwiftUI:

func subscriberDidConnect(toStream subscriberKit: OTSubscriberKit) {
    if let view = subscriber?.view {
        DispatchQueue.main.async {
            self.subView = view
        }
    }
}