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iOS Video Application Recommendations and Best Practices

This guide provides recommendations and best practices for building an iOS video app using the Twilio Programmable Video iOS SDK.

Contents

Helpful Links

Choose Video Settings

Please take a look at this Developing High Quality Video Applications guide to choose the right ConnectOptions when initializing the video call for your use case.

Handle Media Changes

Mute and Unmute the Microphone

When the local participant mutes the microphone, it is recommended to unpublish the microphone track instead of disabling it. When the microphone track is only disabled, the orange indicator in the status bar is still displayed and this could be confusing for users.

var room: Room? // Set when connected to a video room
var micTrack: LocalAudioTrack?

var isLocalMicOn = false {
    didSet {
        guard oldValue != isLocalMicOn else {
            return
        }

        if isLocalMicOn {
            guard let micTrack = LocalAudioTrack(options: nil, enabled: true, name: "mic") else {
                return
            }

            self.micTrack = micTrack
            room?.localParticipant?.publishAudioTrack(micTrack)
        } else {
            guard let micTrack = micTrack else {
                return
            }

            room?.localParticipant?.unpublishAudioTrack(micTrack)
            self.micTrack = nil
        }
    }
}

See the reference iOS video collaboration app for a similar implementation working in an app.

Turn the Camera On and Off

When the local participant turns off the camera, it is recommended to unpublish the camera track instead of disabling it. Unpublishing the camera track will minimize resources consumed and there is no impact to the user experience.

var room: Room? // Set when connected to a video room
var cameraSource: CameraSource?
var cameraTrack: CameraTrack?

var isLocalCameraOn = false {
    didSet {
        guard oldValue != isLocalCameraOn else { 
            return
        }

        if isLocalCameraOn {
            guard 
                let cameraSource = CameraSource(delegate: self), 
                let cameraTrack = LocalVideoTrack(source: cameraSource, enabled: true, name: "camera") 
                let captureDevice = CameraSource.captureDevice(position: .front),
            else {
                return
            }

            cameraSource.startCapture(device: captureDevice, completion: nil)

            room?.localParticipant?.publishVideoTrack(cameraTrack)
            self.cameraSource = cameraSource
            self.cameraTrack = cameraTrack
        } else {
            if let cameraTrack = cameraTrack {
                participant?.unpublishVideoTrack(cameraTrack)
            }

            cameraSource?.stopCapture()
            cameraSource = nil
            cameraTrack = nil
        }
    }
}

See the reference iOS video collaboration app for a similar implementation working in an app.

Display Media Status in the User Interface

When displaying track status in the user interface, check if the track is enabled. Tracks may be disabled instead of unpublished for some edge cases or to optimize the experience for users on a platform that isn't using the iOS Video SDK.

extension RemoteParticipant {
    var isMicOn: Bool {
        // Make sure to use the same track name that your app is using to create the microphone track
        guard let track = participant.remoteAudioTracks.first(where: { $0.trackName == "mic" }) else { 
            return false 
        }

        return track.isTrackSubscribed && track.isTrackEnabled
    }

    var isCameraOn: Bool {
        // Make sure to use the same track name that your app is using to create the camera track
        guard let track = participant.remoteVideoTracks.first(where: { $0.trackName == "camera" }) else { 
            return false 
        }

        return track.isTrackSubscribed && track.isTrackEnabled
    }
}

See the reference iOS video collaboration app for a similar implementation working in an app.

Run the App in the Background

Handle Camera Interruptions

When the app moves to the background, the system will interrupt camera capture. We recommend that you disable the camera track instead of unpublish it, since interruptions can be frequent due to things like notifications. When the camera interruption ends, enable the track again.

var cameraTrack: CameraTrack? // Set when camera is turned on

// CameraSourceDelegate
func cameraSourceWasInterrupted(source: CameraSource, reason: AVCaptureSession.InterruptionReason) {
    cameraTrack?.isEnabled = false
}

func cameraSourceInterruptionEnded(source: CameraSource) {
    cameraTrack?.isEnabled = true
}

See the reference iOS video collaboration app for a similar implementation working in an app.

Handle Audio Interruptions

When another app interrupts audio (e.g. receiving a phone call in the Phone app), audio recording and playback in the video app will be interrupted. This could cause your app to be suspended because it is not playing or recording audio. When the app is suspended the app will be disconnected from the video room.

Handle Errors

This section lists some of the important errors raised by the iOS Video SDK and provides recommendations on how best to handle them in order to provide the optimal user experience.

Connection Errors

These errors are raised when the app is not able to connect to a Room. The app can use the RoomDelegate to receive connection errors. Your app should handle errors that may happen when trying to connect to a Room.

// RoomDelegate function
func roomDidFailToConnect(room: Room, error: Error) {
    // Handle error
}

The following table describes the most common connection errors and proposes ways for the application to handle them:

Error Code Cause Solution
SignalingConnectionError 53000 The client could not establish a connection to Twilio's signaling server User should make sure to have a stable internet connection
SignalingServerBusyError 53006 Twilio's signaling server is too busy to accept new clients User should try joining the Room again after some time
RoomMaxParticipantsExceededError 53105 The Room cannot allow in any more Participants to join Your app should notify the user that the Room is full
RoomNotFoundError 53106 The client attempted to connect to a Room that does not exist If ad-hoc Room creation is disabled, then your app should make sure that the Room is created using the REST API before clients attempt to join
MediaConnectionError 53405 The client failed to establish a media connection with the Room 1. User should make sure to have a stable internet connection
2. If the user is behind a firewall, then it should allow media traffic to and from Twilio to go through

Disconnection Errors

These errors are raised when the app is inadvertently disconnected from the Room. The app can use the RoomDelegate to receive disconnect errors.

// RoomDelegate function
func roomDidDisconnect(room: Room, error: Error?) {
    if let error = error {
        // Handle error
    }
}

The following table describes the most common disconnection errors and proposes ways for the application to handle them:

Error Code Cause Solution
SignalingConnectionDisconnectedError 53001 The client failed to reconnect to Twilio's signaling server after a network disruption or handoff User should make sure to have a stable internet connection
SignalingConnectionTimeoutError 53002 The liveliness checks for the connection to Twilio's signaling server failed, or the current session expired User should rejoin the Room
ParticipantDuplicateIdentityError 53205 Another client joined the Room with the same identity Your app should make sure each client creates an AccessToken with a unique identity string
MediaConnectionError 53405 The client failed to re-establish its media connection with the Room after a network disruption or handoff 1. User should make sure to have a stable internet connection
2. If the user is behind a firewall, then the firewall should allow media traffic to and from Twilio to go through
RoomNotFoundError 53106 The client tried to reconnect to Twilio's signaling server after a network disruption or handoff, but room they had joined ended while they were disconnected Your app should notify user that Room has ended
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