iOS application example to capture stream from device screen

This example can be used to publish WebRTC stream from device screen and a separate audio stream for publishers voice

The main application view is shown below. Inputs:

Application view when screen sharing is started

A special extension process is used to capture video from screen. This pocess works until device is locked or screen cpturing is stopped manually.

Analyzing example code

To analyze the code take ScreenCapturer example version which is available on GitHub.

Classes

1. Import API code

import FPWCSApi2Swift

2. Session creation to publish audio

WCSSession, WCSSession.connect  code

The following parameters are passed to WCSSession constructor:

    @IBAction func publishAudioPressed(_ sender: Any) {
        if (publishAudioButton.title(for: .normal) == "Publish Audio") {
            let options = FPWCSApi2SessionOptions()
                options.urlServer = self.urlField.text
                options.appKey = "defaultApp"
                do {
                    try session = WCSSession(options)
                } catch {
                    print(error)
                }
                ...
                session?.connect()
            changeViewState(publishAudioButton, false)
        } else {
            ...
        }
    }

3. Audio publishing

WCSSession.createStream, WCSStream.publish  code

The following parameters are passed to createStream method:

    func onConnected(_ session:WCSSession) throws {
            let options = FPWCSApi2StreamOptions()
            options.name = publishAudioName.text
            options.constraints = FPWCSApi2MediaConstraints(audio: true, video: false);
            do {
                publishStream = try session.createStream(options)
            } catch {
                print(error);
            }
            ...
            do {
                try publishStream?.publish()
            } catch {
                print(error);
            }
    }

4. Screen capturer extension parameters setup

code

UserDefaults.suiteName parameter must be equal to extension application group id

    @objc func pickerAction() {
        //#WCS-3207 - Use suite name as group id in entitlements
        let userDefaults = UserDefaults.init(suiteName: "group.com.flashphoner.ScreenCapturerSwift")
        userDefaults?.set(urlField.text, forKey: "wcsUrl")
        userDefaults?.set(publishVideoName.text, forKey: "streamName")
        
    }

5. Screen capturer class setup

code

    fileprivate var capturer: ScreenRTCVideoCapturer = ScreenRTCVideoCapturer()

6. Receiving screen capture parameters in extension code

code

    override func broadcastStarted(withSetupInfo setupInfo: [String : NSObject]?) {
        //#WCS-3207 - Use suite name as group id in entitlements
        let userDefaults = UserDefaults.init(suiteName: "group.com.flashphoner.ScreenCapturerSwift")
        let wcsUrl = userDefaults?.string(forKey: "wcsUrl")
        if  wcsUrl != self.wcsUrl || session?.getStatus() != .fpwcsSessionStatusEstablished {
            session?.disconnect()
            session = nil
        }
        self.wcsUrl = wcsUrl ?? self.wcsUrl
        
        let streamName = userDefaults?.string(forKey: "streamName")
        self.streamName = streamName ?? self.streamName
        ...
    }

7. Session creation to publish screen stream

WCSSession, WCSSession.connect  code

        if (session == nil) {
            let options = FPWCSApi2SessionOptions()
            options.urlServer = self.wcsUrl
            options.appKey = "defaultApp"
            do {
                try session = WCSSession(options)
            } catch {
                print(error)
            }
            ...
            session?.connect()
        }

8. Screen stream publishing

WCSSession.createStream, WCSStream.publish  code

The following parameters are passed to createStream method:

    func onConnected(_ session:WCSSession) throws {
        let options = FPWCSApi2StreamOptions()
        options.name = streamName
        options.constraints = FPWCSApi2MediaConstraints(audio: false, videoCapturer: capturer);

        try publishStream = session.createStream(options)
        ...        
        try publishStream?.publish()
    }