Screen Sharing

Add screen sharing in CometChat Calls SDK v5 on iOS with presenter controls, permissions, and in-call display behavior.

View screen shares from other participants during a call. The iOS SDK can receive and display screen shares initiated from web clients.

The iOS Calls SDK does not support initiating screen sharing. Screen sharing can only be started from web clients. iOS participants can view shared screens.

How It Works

When a web participant starts screen sharing:

1. The SDK receives the screen share stream
2. The call layout automatically adjusts to display the shared screen prominently
3. iOS participants can view the shared content

Listen for Screen Share Events

Monitor when participants start or stop screen sharing:

Swift

class CallViewController: UIViewController, ParticipantEventListener {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        CallSession.shared.addParticipantEventListener(self)
    }
    
    deinit {
        CallSession.shared.removeParticipantEventListener(self)
    }
    
    func onParticipantStartedScreenShare(participant: Participant) {
        print("\(participant.name ?? "") started screen sharing")
        // Layout automatically adjusts to show shared screen
    }

    func onParticipantStoppedScreenShare(participant: Participant) {
        print("\(participant.name ?? "") stopped screen sharing")
        // Layout returns to normal view
    }

    // Other callbacks...
    func onParticipantJoined(participant: Participant) {}
    func onParticipantLeft(participant: Participant) {}
    func onParticipantListChanged(participants: [Participant]) {}
    func onParticipantAudioMuted(participant: Participant) {}
    func onParticipantAudioUnmuted(participant: Participant) {}
    func onParticipantVideoPaused(participant: Participant) {}
    func onParticipantVideoResumed(participant: Participant) {}
    func onParticipantStartedRecording(participant: Participant) {}
    func onParticipantStoppedRecording(participant: Participant) {}
    func onParticipantHandRaised(participant: Participant) {}
    func onParticipantHandLowered(participant: Participant) {}
    func onDominantSpeakerChanged(participant: Participant) {}
}

Objective-C

@interface CallViewController () <ParticipantEventListener>
@end

@implementation CallViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [[CallSession shared] addParticipantEventListener:self];
}

- (void)dealloc {
    [[CallSession shared] removeParticipantEventListener:self];
}

- (void)onParticipantStartedScreenShareWithParticipant:(Participant *)participant {
    NSLog(@"%@ started screen sharing", participant.name);
    // Layout automatically adjusts to show shared screen
}

- (void)onParticipantStoppedScreenShareWithParticipant:(Participant *)participant {
    NSLog(@"%@ stopped screen sharing", participant.name);
    // Layout returns to normal view
}

// Other callbacks...

@end

Track Who Is Sharing

Participant carries no screen-share property, and the SDK exposes no getter for one. Track the current presenter yourself from the start/stop callbacks.

These callbacks fire only when a share starts or stops. A client that joins mid-call cannot discover a share that was already in progress before it joined.

Swift

// uids of participants currently sharing.
private var presenterUIDs = Set<String>()

func onParticipantStartedScreenShare(participant: Participant) {
    guard let uid = participant.uid else { return }
    DispatchQueue.main.async {
        self.presenterUIDs.insert(uid)
        print("\(participant.name ?? uid) started sharing their screen")
    }
}

func onParticipantStoppedScreenShare(participant: Participant) {
    guard let uid = participant.uid else { return }
    DispatchQueue.main.async {
        self.presenterUIDs.remove(uid)
    }
}

// A participant who leaves while sharing never sends a stop event.
func onParticipantLeft(participant: Participant) {
    guard let uid = participant.uid else { return }
    DispatchQueue.main.async { self.presenterUIDs.remove(uid) }
}

Objective-C

@property (nonatomic, strong) NSMutableSet<NSString *> *presenterUIDs;

- (void)onParticipantStartedScreenShareWithParticipant:(Participant *)participant {
    NSString *uid = participant.uid;
    if (!uid) { return; }
    dispatch_async(dispatch_get_main_queue(), ^{
        [self.presenterUIDs addObject:uid];
        NSLog(@"%@ started sharing their screen", participant.name ?: uid);
    });
}

- (void)onParticipantStoppedScreenShareWithParticipant:(Participant *)participant {
    NSString *uid = participant.uid;
    if (!uid) { return; }
    dispatch_async(dispatch_get_main_queue(), ^{
        [self.presenterUIDs removeObject:uid];
    });
}