In-Session Communication

The iOS SDK provides methods for chat, custom signalling, file sharing, screen sharing, canvas streaming, annotation, and live transcription within an active video session.

Chat

Send a Chat Message

Use sendMessage:isBroadCast:recipientIDs: to send a text message to all participants or to specific recipients. No stream publishing or subscription is required to exchange messages — the method works as soon as the room is connected.

Detail	Value
Class	`EnxRoom`
Method	`-(void)sendMessage:(NSString )message isBroadCast:(BOOL)broadcast recipientIDs:(NSArray )clientIds`

Supports public (broadcast to all), private (one recipient), and group (multiple recipients) messaging.

Parameters

Parameter	Type	Description
`message`	String	Message text.
`isBroadCast`	Boolean	`true` for public broadcast; `false` for private or group messaging.
`recipientIDs`	Array	Array of Client IDs for private or group messaging. Pass `nil` when broadcasting.

Delegate Methods

Delegate	Description
`-room:didACKSendMessage`	Acknowledgment delivered to the sender.
`-room:didMessageReceived`	Recipients receive the message.

let recipients = ["clientId1", "clientId2"]

// Public message to all
room.sendMessage("Hello everyone!", isBroadCast: true, recipientIDs: nil)

// Private message to specific recipients
room.sendMessage("Hello!", isBroadCast: false, recipientIDs: recipients)

func room(_ room: EnxRoom?, didMessageReceived data: [Any]?) {
    // data contains the incoming message
}

NSArray *recipients = @[@"clientId1", @"clientId2"];

// Public message to all
[room sendMessage:@"Hello everyone!" isBroadCast:YES recipientIDs:nil];

// Private message to specific recipients
[room sendMessage:@"Hello!" isBroadCast:NO recipientIDs:recipients];

- (void)room:(EnxRoom *)room didMessageReceived:(NSArray *)data {
    // data contains the incoming message
}

Edit a Chat Message

Introduced in iOS SDK 3.0.20 (May 2025).

To update a message that has already been sent, call transactMessage: with a dictionary that includes the original message ID and the corrected text. Set type to "chat-update".

Detail	Value
Class	`EnxRoom`
Method	`-(void)transactMessage:(NSDictionary *)options` with `type: "chat-update"`

Parameters

Parameter	Type	Description
`message`	String	Updated message text.
`messageId`	String	Message ID of the original message (received in `didMessageReceived` / `didACKSendMessage`).
`type`	String	Use `"chat-update"`.

Delegate Methods

Delegate	Description
`-room:didACKUpdateMessage`	Sender acknowledgment.
`-room:didMessageUpdate`	Recipients receive the edited message.

let editOptions: [String: Any] = [
    "message"  : "This is my edited message",
    "messageId": "MSG_ID",
    "type"     : "chat-update"
]

room.transactMessage(editOptions)

func didACKUpdateMessage(_ data: [Any]?) {
    // Edit acknowledged
}

func didMessageUpdate(_ data: [Any]?) {
    // Recipients notified of edited message
}

NSDictionary *editOptions = @{
    @"message":   @"This is my edited message",
    @"messageId": @"MSG_ID",
    @"type":      @"chat-update"
};

[room transactMessage:editOptions];

- (void)didACKUpdateMessage:(NSArray *)data {
    // Edit acknowledged
}

- (void)didMessageUpdate:(NSArray *)data {
    // Recipients notified of edited message
}

Delete a Chat Message

Introduced in iOS SDK 3.0.20 (May 2025).

To remove a sent message, call transactMessage: with a dictionary containing the message ID and type: "chat-delete". The server notifies all original recipients so their UIs can remove the message.

Detail	Value
Class	`EnxRoom`
Method	`-(void)transactMessage:(NSDictionary *)options` with `type: "chat-delete"`

Parameters

Parameter	Type	Description
`messageId`	String	Message ID to delete.
`type`	String	Use `"chat-delete"`.

Delegate Methods

Delegate	Description
`-room:didACKDeleteMessage`	Sender acknowledgment.
`-room:didMessageDelete`	Recipients notified of deletion.

let deleteOptions: [String: Any] = [
    "messageId": "MSG_ID",
    "type"     : "chat-delete"
]

room.transactMessage(deleteOptions)

func didACKDeleteMessage(_ data: [Any]?) {
    // Delete acknowledged
}

func didMessageDelete(_ data: [Any]?) {
    // Recipients notified of deletion
}

NSDictionary *deleteOptions = @{
    @"messageId": @"MSG_ID",
    @"type":      @"chat-delete"
};

[room transactMessage:deleteOptions];

- (void)didACKDeleteMessage:(NSArray *)data {
    // Delete acknowledged
}

- (void)didMessageDelete:(NSArray *)data {
    // Recipients notified of deletion
}

Custom Signalling

Send Custom Data

Use custom signalling to send structured business data between participants — polls, instructions, or any application-specific payload that does not fit the standard chat message structure. Pass any NSDictionary payload to one or more participants without wrapping it in a chat message.

Detail	Value
Class	`EnxRoom`
Method	`-(void)sendUserData:(NSDictionary )Message isBroadCast:(BOOL)broadcast recipientIDs:(NSArray )clientIds`

Parameters

Parameter	Type	Description
`Message`	Object	`NSDictionary` with any custom keys.
`isBroadCast`	Boolean	`true` for broadcast; `false` for targeted delivery.
`recipientIDs`	Array	Client IDs when not broadcasting.

Delegate: -room:didUserDataReceived — fires on each recipient with the custom dictionary payload.

Error codes: 5127 — data transfer rate exceeds the 100 KB/s limit.

let customData: [String: Any] = [
    "sender" : "Sender Name",
    "message": "Custom payload",
    "type"   : "poll"
]

let recipients = ["clientId1"]
room.sendUserData(customData, broadCast: false, recipientIDs: recipients)

func room(_ room: EnxRoom?, didUserDataReceived data: [Any]?) {
    // Received custom signal
}

NSDictionary *customData = @{
    @"sender":  @"Sender Name",
    @"message": @"Custom payload",
    @"type":    @"poll"
};

NSArray *recipients = @[@"clientId1"];
[room sendUserData:customData broadCast:NO recipientIDs:recipients];

- (void)room:(EnxRoom *)room didUserDataReceived:(NSArray *)data {
    // Received custom signal
}

Available in iOS SDK 1.5.3 and later. Requires iOS 13 or later.

Upload a File for Sharing

Call shareFiles:isBroadcast:clientIds: to launch the system file picker and begin an upload. The position parameter controls where the picker sheet appears on screen using the EnxFilePosition enum. Only one file can be in flight per upload request.

Detail	Value
Class	`EnxRoom`
Method	`-(void)shareFiles:(EnxFilePosition)position isBroadcast:(BOOL)isBroadcast clientIds:(NSArray *)clientIds`

Parameters

Parameter	Type	Description
`position`	Enumerated	Placement of the file picker UI: `Top`, `Bottom`, or `Center`.
`isBroadcast`	Boolean	`true` to share with all participants; `false` for selected users.
`clientIds`	Array	Client IDs when not broadcasting.

Sender Delegate Methods

Delegate	Description
`-room:didInitFileUpload`	Upload process has started.
`-room:didFileUploaded`	File successfully uploaded.
`-room:didFileUploadFailed`	Upload failed.

Receiver Delegate Methods

Delegate	Description
`-room:didFileUploadStarted`	File upload is in progress — receiver is notified.
`-room:didFileAvailable`	File is ready to download.

room.shareFiles(Top, isBroadcast: true, clientIds: nil)

func room(_ room: EnxRoom?, didInitFileUpload data: [Any]?) {
    // Upload started
}

func room(_ room: EnxRoom?, didFileUploaded data: [Any]?) {
    // Upload complete
}

func room(_ room: EnxRoom?, didFileAvailable data: [Any]?) {
    // Receiver: file ready to download
}

[room shareFiles:Top isBroadcast:YES clientIds:nil];

- (void)room:(EnxRoom *)room didInitFileUpload:(NSArray *)data {
    // Upload started
}

- (void)room:(EnxRoom *)room didFileUploaded:(NSArray *)data {
    // Upload complete
}

- (void)room:(EnxRoom *)room didFileAvailable:(NSArray *)data {
    // Receiver: file ready to download
}

Download a Shared File

First retrieve available files using -(NSArray *)getAvailableFiles, then initiate a download. Set autoSave to YES to let the SDK save images and videos directly to the device, or NO to receive raw Base64 data and handle storage yourself.

Detail	Value
Method	`-(void)downloadFile:(NSDictionary *)file autoSave:(BOOL)flag`

Parameters

Parameter	Type	Description
`file`	Object	File object received from `didFileAvailable`.
`autoSave`	Boolean	`true` to auto-save images/videos; `false` to receive Base64 raw data.

Callbacks

Delegate	Description
`-room:didFileDownloaded`	File downloaded successfully.
`-room:didFileDownloadFailed`	Download failed.

// Get available files
room.getAvailableFiles()

// Initiate download
room.downloadFile(fileObject, autoSave: true)

func room(_ room: EnxRoom?, didFileDownloaded data: String?) {
    // File downloaded
}

func room(_ room: EnxRoom?, didFileDownloadFailed data: [Any]?) {
    // Download failed
}

// Get available files
[room getAvailableFiles];

// Initiate download
[room downloadFile:fileObject autoSave:YES];

- (void)room:(EnxRoom *)room didFileDownloaded:(NSString *)data {
    // File downloaded
}

- (void)room:(EnxRoom *)room didFileDownloadFailed:(NSArray *)data {
    // Download failed
}

Cancel File Upload

Each upload is assigned a numeric job ID. Use that ID to cancel a specific upload, or call cancelAllUploads to stop all in-flight uploads at once.

-(void)cancelUpload:(int)jobID — cancel a specific upload by job ID.
-(void)cancelAllUploads — cancel all uploads.

Callback: didFileUploadCancelled

Upload Error Codes

Code	Meaning
5089	Storage permission denied.
5090	Auto-save to device failed.
5091	File sharing not available.
5092	Maximum one file per request.
1185	File exceeds the maximum allowed size.
1182	Upload failed.
5098	Cannot cancel — upload already complete.
5099	Invalid upload job ID.
5100	Corrupt file detected.
5102	No WebView context available.

Cancel File Download

-(void)cancelDownload:(int)jobID — cancel a specific download.
-(void)cancelAllDownloads — cancel all downloads.

Callback: didFileDownloadCancelled

Download Error Codes

Code	Meaning
5089	Storage permission denied.
5090	Auto-save to device failed.
1183	Download failed.
1181	File not available in this context.
5101	File already downloaded.

Enable screen sharing during room creation: { "screen_share": true }. Subscribers receive the screen stream on Stream ID 101.

Screen sharing publishes the device's entire screen as a dedicated media stream at 6 fps. Unlike regular streams, the screen share continues even when the user moves the app to the background, making it suitable for walkthroughs, support sessions, and presentations.

Call startScreenShare on your EnxRoom instance. The SDK coordinates with a Broadcast Extension process that handles screen capture at the OS level. Two separate delegate callbacks reflect the two separate processes involved.

Detail	Value
Class	`EnxRoom`
Method	`- (void)startScreenShare`

Delegate Methods

Delegate	Description
`-didStartBroadCast`	Broadcast extension receives this when the screen stream is publishing.
`-didStartScreenShareACK`	Endpoint acknowledgment when the screen stream starts.

enxRoom.startScreenShare()

func didStartBroadCast(_ data: [Any]?) {
    // Broadcast extension started
}

func room(_ room: EnxRoom?, didStartScreenShareACK data: [Any]?) {
    // Screen sharing started
}

[enxRoom startScreenShare];

- (void)didStartBroadCast:(NSArray *)data {
    // Broadcast extension started
}

- (void)room:(EnxRoom *)room didStartScreenShareACK:(NSArray *)data {
    // Screen sharing started
}

Detail	Value
Method	`-(void)stopScreenShare`

Delegate Methods

Delegate	Description
`-didStoppedBroadCast`	Broadcast extension when unpublishing.
`-didStopScreenShareACK`	Endpoint acknowledgment when screen sharing stops.

enxRoom.stopScreenShare()

func didStoppedBroadCast(_ data: [Any]?) {
    // Broadcast extension stopped
}

func room(_ room: EnxRoom?, didStopScreenShareACK data: [Any]?) {
    // Screen sharing stopped
}

[enxRoom stopScreenShare];

- (void)didStoppedBroadCast:(NSArray *)data {
    // Broadcast extension stopped
}

- (void)room:(EnxRoom *)room didStopScreenShareACK:(NSArray *)data {
    // Screen sharing stopped
}

exitScreenShare signals the Broadcast Extension to exit the session entirely. This must be called from the Broadcast Extension target, not the main app.

Detail	Value
Method	`-(void)exitScreenShare`

Delegate Methods

Delegate	Description
`-didExitScreenShareACK`	Parent app acknowledgment.
`-didRequestedExitRoom`	Fires on the screen sharing child client — triggers it to stop broadcast and disconnect.

Error code: 5137 — screen sharing is not currently running.

Moderator-only feature. Available in iOS SDK 2.1.2 and later. Also stops any active canvas stream.

Moderators can forcibly end any active screen share or canvas stream across the room with a single call. This is useful for regaining control of the session if a participant has left sharing running unintentionally.

Detail	Value
Method	`-(void)stopAllSharing`
Callback	`didACKStopAllSharing`

enxRoom.stopAllSharing()

func room(_ room: EnxRoom?, didStopAllSharingACK data: [Any]?) {
    // All sharing stopped
}

[enxRoom stopAllSharing];

- (void)room:(EnxRoom *)room didStopAllSharingACK:(NSArray *)data {
    // All sharing stopped
}

Canvas Streaming

Enable canvas streaming during room creation: { canvas: true }. The canvas stream is received on Stream ID 102.

Canvas streaming lets a participant publish any UIView as a dedicated video stream. This is the right tool when you need to share custom content — a presentation slide, a whiteboard, a data visualisation, or any arbitrary view hierarchy — without sharing the entire screen.

Start Canvas Streaming

Pass the view you want to stream to startCanvas:. The SDK captures the view's render output and publishes it as Stream ID 102.

Detail	Value
Class	`EnxRoom`
Method	`(void)startCanvas:(UIView *)view`

Delegate Methods

Delegate	Description
`-room:didStartCanvasACK`	Acknowledgment to the publisher.
`-room:didCanvasStarted`	Notification to all participants — use this to render the stream.

room.startCanvas(myUIView)

func room(_ room: EnxRoom?, didStartCanvasACK data: [Any]?) {
    // Publisher: canvas streaming started
}

func room(_ room: EnxRoom?, didCanvasStarted stream: EnxStream?) {
    // All participants: render the canvas stream
    stream?.enxPlayer?.frame = yourFrame
    yourView.addSubview(stream!.enxPlayer!)
}

[room startCanvas:myUIView];

- (void)room:(EnxRoom *)room didStartCanvasACK:(NSArray *)data {
    // Publisher: canvas streaming started
}

- (void)room:(EnxRoom *)room didCanvasStarted:(EnxStream *)stream {
    // All participants: render the canvas stream
    stream.enxPlayer.frame = yourFrame;
    [yourView addSubview:stream.enxPlayer];
}

Error Codes

Code	Meaning
5105	Canvas already active.
5107	A canvas request is already in progress.
5103	Canvas or screen sharing is already running — only one can be active at a time.
5110	Canvas publish failed.

Stop Canvas Streaming

Detail	Value
Method	`-(void)stopCanvas`

Delegate Methods

Delegate	Description
`-room:didStoppedCanvasACK`	Acknowledgment to the publisher.
`-room:didCanvasStopped`	Notification to all participants — remove the stream from the UI.

room.stopCanvas()

func room(_ room: EnxRoom?, didCanvasStopped stream: EnxStream?) {
    stream?.enxPlayer?.removeFromSuperview()
}

[room stopCanvas];

- (void)room:(EnxRoom *)room didCanvasStopped:(EnxStream *)stream {
    [stream.enxPlayer removeFromSuperview];
}

Annotation

Available in iOS SDK 1.5.6 and later. Requires canvas streaming enabled in the room. Supports Landscape mode only.

Annotation lets a participant draw on top of a remote stream in real time. The EnxToolBar UI component provides drawing tools (pen, shapes, eraser, and more) that the annotating participant can use without additional setup. The annotation layer is composited over the selected stream and is visible to all participants.

Instantiate EnxToolBar and add it to your view hierarchy before starting annotation. Position it so it does not obscure the stream it will annotate.

let toolBar = EnxToolBar(frame: CGRect(x: x, y: y, width: width, height: height))

EnxToolBar *toolBar = [[EnxToolBar alloc] initWithFrame:CGRectMake(x, y, width, height)];

Start Annotation

Pass the remote EnxStream you want to annotate. The SDK validates that the stream is valid and that no other annotation or canvas operation is in progress.

Detail	Value
Class	`EnxRoom`
Method	`-(void)startAnnotation:(EnxStream *)stream`

Delegate Methods

Delegate	Description
`-room:didStartAnnotationACK:`	Acknowledgment to the annotator.
`-room:didAnnotationStarted:`	Notification to all participants.

Stop Annotation

Detail	Value
Method	`-(void)stopAnnotation`

Delegate Methods

Delegate	Description
`-room:didStoppedAnnotationACK:`	Acknowledgment to the annotator.
`-room:didAnnotationStopped:`	Notification to all participants.

enxRoom.startAnnotation(remoteStream)
enxRoom.stopAnnotation()

func room(_ room: EnxRoom?, didStartAnnotationACK data: [Any]?) { }
func room(_ room: EnxRoom?, didAnnotationStarted data: [Any]?) { }
func room(_ room: EnxRoom?, didStoppedAnnotationACK data: [Any]?) { }
func room(_ room: EnxRoom?, didAnnotationStopped data: [Any]?) { }

[enxRoom startAnnotation:remoteStream];
[enxRoom stopAnnotation];

- (void)room:(EnxRoom *)room didStartAnnotationACK:(NSArray *)data { }
- (void)room:(EnxRoom *)room didAnnotationStarted:(NSArray *)data { }
- (void)room:(EnxRoom *)room didStoppedAnnotationACK:(NSArray *)data { }
- (void)room:(EnxRoom *)room didAnnotationStopped:(NSArray *)data { }

Annotation Error Codes

Code	Meaning
5093	Access denied — insufficient permissions.
5104	Annotation already active.
5106	A start-annotation request is already in progress.
5108	Invalid stream — cannot annotate this stream.
5109	Annotation publish failed.
5112	Landscape mode required.
5094	Stop annotation already in progress.

Live Transcription

Live transcription converts speech from active talkers to text in real time and broadcasts it to subscribers. The transcription process starts with the first subscriber and stops when the last unsubscribes — unless auto_transcribe is enabled, in which case it runs for the full session.

Live Transcription is a subscription-based service. Contact your EnableX Sales or Account Manager to enable it for your account before using any of the APIs below.

Room Configuration

Include a live_transcription object in the room creation payload to control transcription behaviour at the room level:

Setting	Type	Description
`live_transcription.language`	String	Required. Language code, e.g. `"english_us"`.
`live_transcription.auto_transcribe`	Boolean	Default `false`. Set `true` to auto-start at session start and save to file.
`live_transcription.enable`	Boolean	Default `true`. Set `false` to disable transcription for this room.

Start Live Transcription

Two methods are available depending on the desired scope:

Scope	Method
Self only	`-(void)startLiveTranscription:(NSString *)language`
Entire room	`-(void)startLiveTranscriptionForRoom:(NSString *)language`

The language parameter is optional; it defaults to "english_us". If room-level transcription is already running when a second participant calls this method, they are subscribed to the existing process rather than starting a new one.

Delegate Methods

Delegate	Description
`-room:didACKStartLiveTranscription`	Acknowledgment to the caller.
`-room:didSelfTranscriptionOn`	Self-transcription enabled for this endpoint.
`-room:didRoomTranscriptionOn`	Room-level transcription enabled — sent to all participants.
`-room:didTranscriptionEvents`	Receives transcribed text. Payload includes `type` (`speech_recognising` / `speech_recognised`), `text`, `duration`, and `clientId`.

enxRoom.startLiveTranscriptionForRoom("english_us")

func room(_ room: EnxRoom?, didRoomTranscriptionOn data: [Any]?) {
    // Room-level transcription started
}

func room(_ room: EnxRoom?, didSelfTranscriptionOn data: [Any]?) {
    // Self transcription started
}

func room(_ room: EnxRoom?, didTranscriptionEvents data: [Any]?) {
    // Receive transcribed text in real time
    // data: [{ "type": "speech_recognised", "text": "...", "clientId": "..." }]
}

[enxRoom startLiveTranscriptionForRoom:@"english_us"];

- (void)room:(EnxRoom *)room didRoomTranscriptionOn:(NSArray *)data {
    // Room-level transcription started
}

- (void)room:(EnxRoom *)room didSelfTranscriptionOn:(NSArray *)data {
    // Self transcription started
}

- (void)room:(EnxRoom *)room didTranscriptionEvents:(NSArray *)data {
    // Receive transcribed text in real time
    // data: [{ "type": "speech_recognised", "text": "...", "clientId": "..." }]
}

Error codes: 3002 — not subscribed or transcription is already in progress.

Stop Live Transcription

Calling stopLiveTranscription unsubscribes the caller from the transcription feed. The underlying transcription process stops when all subscribers have unsubscribed — unless auto_transcribe is enabled, in which case it continues until the session ends.

Scope	Method
Self only	`-(void)stopLiveTranscription`

Delegate Methods

Delegate	Description
`-room:didACKStopLiveTranscription`	Acknowledgment to the caller.
`-room:didSelfTranscriptionOff`	Self-transcription turned off for this endpoint.
`-room:didRoomTranscriptionOff`	Room-level transcription turned off — sent to all participants.

enxRoom.stopLiveTranscription()

func room(_ room: EnxRoom?, didRoomTranscriptionOff data: [Any]?) {
    // Room transcription stopped
}

func room(_ room: EnxRoom?, didSelfTranscriptionOff data: [Any]?) {
    // Self transcription stopped
}

[enxRoom stopLiveTranscription];

- (void)room:(EnxRoom *)room didRoomTranscriptionOff:(NSArray *)data {
    // Room transcription stopped
}

- (void)room:(EnxRoom *)room didSelfTranscriptionOff:(NSArray *)data {
    // Self transcription stopped
}

← Stream Management Session Management →

In-Session Communication

Send a Chat Message

Parameters

Delegate Methods

Edit a Chat Message

Parameters

Delegate Methods

Delete a Chat Message

Parameters

Delegate Methods

Send Custom Data

Parameters

Upload a File for Sharing

Parameters

Sender Delegate Methods

Receiver Delegate Methods

Download a Shared File

Parameters

Callbacks

Cancel File Upload

Upload Error Codes

Cancel File Download

Download Error Codes

Start Screen Sharing

Delegate Methods

Stop Screen Sharing

Delegate Methods

Exit Screen Sharing

Delegate Methods

Force Stop Screen Sharing

Start Canvas Streaming

Delegate Methods

Error Codes

Stop Canvas Streaming

Delegate Methods

Add Annotation Toolbar

Start Annotation

Delegate Methods

Stop Annotation

Delegate Methods

Annotation Error Codes

Room Configuration

Start Live Transcription

Delegate Methods

Stop Live Transcription

Delegate Methods