Screen share in a 1-to-1 call
This page provides a code example for screen share in a 1-to-1 call.
Prerequisites (iOS only)
Before implementing screen share in your iOS application, you must do the following:
- The application must implement Broadcast Upload Extension or equivalents to capture screen share.
- To implement Broadcast Upload Extension, in Xcode, add a new Target to your project, select "Broadcast Upload Extension" template, and activate the extension.
- Define a port number, a reception token, and a transmission token that will be used for screen share stream transmission.
Sender - Start sending screen share
The code implementation for starting screen share differs between iOS and macOS.
iOS
Set the screen share key in PlanetKit
The app client of the sender needs to specify predefined port number, reception token, and transmission token, and sets it in withEnableScreenShareKey(broadcastPort:broadcastPeerToken:broadcastMyToken:) of PlanetKitMakeCallSettingBuilder (caller) or PlanetKitVerifyCallSettingBuilder (callee).
// If the sender is a caller
var settingsBuilder = try! PlanetKitMakeCallSettingBuilder()
.withEnableScreenShareKey(broadcastPort: PORT_NUMBER, broadcastPeerToken: "USER_DEFINED_TOKEN_EXT", broadcastMyToken: "USER_DEFINED_TOKEN_APP")
// If the sender is a callee
var settingsBuilder = try! PlanetKitVerifyCallSettingBuilder()
.withEnableScreenShareKey(broadcastPort: PORT_NUMBER, broadcastPeerToken: "USER_DEFINED_TOKEN_EXT", broadcastMyToken: "USER_DEFINED_TOKEN_APP")
Implement a screen capturing and transmission module
Implement a screen capturing module that establishes connection between your app and the SDK through NWConnection.
class BroadcastSender {
private enum State {
case started
case handshaking
case connected
case failed
}
private let connection: NWConnection
private let queue = DispatchQueue(label: "BroadcastSender.Queue")
static func connection(broadcastPort : UInt16) throws -> NWConnection {
guard let port = NWEndpoint.Port(rawValue: broadcastPort) else {
throw Error.invalidPort
}
let options = NWProtocolTCP.Options()
options.noDelay = true
return NWConnection(host: .ipv4(.loopback), port: port, using: .init(tls: nil, tcp: options))
}
init(broadcastPort: UInt16, rxToken : String, txToken : String) throws {
self.delegate = delegate
self.rxToken = rxToken
self.txToken = txToken
connection = try BroadcastSender.connection(broadcastPort: broadcastPort)
connection.stateUpdateHandler = { [weak self] in
self?.handleConnection(newState: $0)
}
connection.start(queue: DispatchQueue(label: "BroadcastSender.NetworkQueue"))
}
func handShake() {
guard state == .started, let data = txToken.data(using: .utf8) else {
return
}
state = .handshaking
connection.send(content: data, completion: .contentProcessed({ (error) in
self.handShakeProcessed(error: error)
}))
}
func sendVideo(sampleBuffer: CMSampleBuffer) throws {
guard state == .connected,
!sending else {
return
}
try queue.sync {
let data: Data?
// create data with CMSampleBuffer
connection.send(data, completion: .contentProcessed({(error) in NSLog("data processed \(error)")}))
}
}
func handShakeProcessed(error: NWError?) {
queue.sync {
if let error = error {
didFail(error: error)
} else {
handShakeAck()
}
}
}
func handShakeAck() {
guard state == .handshaking, let token = rxToken.data(using: .utf8) else {
return
}
connection.receive(minimumIncompleteLength: token.count, maximumLength: token.count) { (data, context, final, error) in
self.handShakeAckProcessed(data: data, error: error)
}
}
func handShakeAckProcessed(data: Data?, error: NWError?) {
queue.sync {
guard state == .handshaking, let token = rxToken.data(using: .utf8) else {
return
}
if data == token {
state = .connected
} else {
didFail(error: .rejected)
}
}
}
func handleConnection(newState: NWConnection.State) {
queue.sync {
switch newState {
case .ready:
handShake()
case .waiting(let error), .failed(let error):
didFail(error: error)
default:
break
}
}
}
}
If connection is successfully established, you must send screen share streams to the created NWConnection. Implement the SampleHandler class to send the captured screen share streams.
class SampleHandler: RPBroadcastSampleHandler {
private var sender: BroadcastSender?
...
override func broadcastFinished() {
// User has requested to finish the broadcast.
sender?.cancel()
sender = nil
}
let rxToken : String = "USER_DEFINED_TOKEN_APP"
let txToken : String = "USER_DEFINED_TOKEN_EXT"
let broadcastPort : UInt16 = PORT_NUMBER
override func processSampleBuffer(_ sampleBuffer: CMSampleBuffer, with sampleBufferType: RPSampleBufferType) {
switch sampleBufferType {
case RPSampleBufferType.video:
do {
if let sender = sender {
try autoreleasepool {
try sender.sendVideo(sampleBuffer: sampleBuffer)
}
} else {
sender = try BroadcastSender(delegate: self, broadcastPort: broadcastPort, rxToken: rxToken, txToken: txToken)
}
} catch {
finish(error: error)
}
break
...
}
}
private func finish(error: Error) {
sender?.cancel()
sender = nil
if let description = (error as? LocalizedError)?.errorDescription {
self.finishBroadcastWithError(NSError(domain: "BroadcastSender.ErrorDomain", code: 0, userInfo: [NSLocalizedFailureReasonErrorKey: description]))
} else {
self.finishBroadcastWithError(error)
}
}
}
Start screen share on PlanetKit
Implement didStartMyBroadcast() of PlanetKitCallDelegate. To start sending the screen share stream, call startMyScreenShare() in didStartMyBroadcast().
extension VideoCallViewController: PlanetKitCallDelegate {
...
func didStartMyBroadcast(_ call: PlanetKitCall) {
NSLog("Broadcast: start")
DispatchQueue.main.async {
call.startMyScreenShare() { success in
guard success else {
return
}
}
}
}
...
}
macOS
Collect the devices for screen capture and select one from them.
func collectCaptureDevices() -> [PlanetKitScreenCaptureDevice] {
var captureDevices = [PlanetKitScreenCaptureDevice]()
autoreleasepool {
for display in PlanetKitScreen.shared.displays {
let name: String
if let screen = NSScreen.screens.first(where: { $0.displayID == display.displayID }) {
name = screen.localizedName
}
...
captureDevices.append(PlanetKitScreenCaptureDevice(display: display))
}
let windows = PlanetKitScreen.shared.windows.filter {
$0.sharingType != .none &&
$0.alpha > 0 &&
$0.level == kCGNormalWindowLevel
}
let myAppId = Bundle.main.bundleIdentifier
for window in windows {
guard let image = window.image, window.sharingType != .none, window.bundleId != nil else {
continue
}
if myAppId == window.bundleId {
continue
}
...
captureDevices.append(PlanetKitScreenCaptureDevice(window: window))
}
}
return captureDevices
}
To start sending screen share, call startMyScreenShare().
func startMyScreenShare(_ device: PlanetKitScreenCaptureDevice) {
...
call.startMyScreenShare(device: device) { success in
guard success else { return }
// UI code here if success
}
}
Sender - Stop sending screen share
The code implementation for stopping screen share differs between iOS and macOS.
iOS
Implement didFinishMyBroadcast() and didErrorMyBroadcast() of PlanetKitCallDelegate. To stop screen share, call stopMyScreenShare() in didFinishMyBroadcast() and didErrorMyBroadcast().
extension VideoCallViewController: PlanetKitCallDelegate {
...
func didFinishMyBroadcast(_ call: PlanetKitCall) {
NSLog("Broadcast: finish")
DispatchQueue.main.async {
self.call?.stopMyScreenShare() { success in
}
}
}
func didErrorMyBroadcast(_ call: PlanetKitCall, error: PlanetKitScreenShare.BroadcastError) {
NSLog("Broadcast: error \(error)")
DispatchQueue.main.async {
self.call?.stopMyScreenShare() { success in
}
}
}
}
macOS
To stop screen share, call stopMyScreenShare().
call.stopMyScreenShare() { success in
self.delegate?.screenShare(self, willDismiss: dismiss)
}
Receiver - Receive screen share update events
Check whether a peer's screen share has started or stopped through the peerDidStartScreenShare or peerDidStopScreenShare event of PlanetKitCallDelegate.
extension VideoCallViewController: PlanetKitCallDelegate {
...
func peerDidStartScreenShare(_ call: PlanetKitCall) {
NSLog("peer screen share started")
// UI code here
DispatchQueue.main.async {
self.setPeerScreenShareEnabled(true)
}
}
func peerDidStopScreenShare(_ call: PlanetKitCall, reason: Int32) {
NSLog("peer screen share stopped")
// UI code here
DispatchQueue.main.async {
self.setPeerScreenShareEnabled(false)
}
}
}
Receiver - Render a peer's screen share video
You can display the shared screen by adding a screen share view after the peerDidStartScreenShare event occurs.
func setPeerScreenShareEnabled(_ enable: Bool) {
if enable {
let newView = PlanetKitMTKView(frame: view.bounds, device: nil)
view.addSubview(newView)
self.screenShareView = newView
call.addPeerScreenShareView(delegate: newView)
...
} else {
...
}
}
Receiver - Remove a peer's screen share video
If you do not wish to render the peer's shared screen, you can remove the screen share view from PlanetKitCall.
func setPeerScreenShareEnabled(_ enable: Bool) {
if enable {
...
} else {
if let oldView = screenShareView {
oldView.removeFromSuperview()
screenShareView = nil
call.removePeerScreenShareView(delegate: oldView)
}
}
}