Nexacon Flutter SDK #

A comprehensive Flutter SDK for Nexacon API — providing plug-and-play P2P audio/video calling with WebRTC and NX signaling, plus real-time messaging with presence and read receipts.

Table of Contents #

Features
Installation
Platform Requirements
Platform Configuration
Quick Start — Outgoing Call
Quick Start — Incoming Call
Advanced Usage
Real-Time Messaging
Foldable Device Support
Call States
API Reference
Troubleshooting

Features #

Simplified API: Make or receive calls in 3 steps with NexaconSDK
P2P Calling: Full WebRTC peer-to-peer audio/video calling with automatic signaling
NX Token Management: Automatic token generation, validation, and client authentication
Incoming Call Support: initialize() + acceptCall() for clean incoming call handling
Consecutive Call Safety: SDK automatically resets all internal state after each call — safe for back-to-back calls
Stale Signal Guard: Signaling messages from previous calls are filtered by room ID and cancelled subscription — no ghost call_end events
Real-Time Messaging: Instant messaging with typing indicators and read receipts
Presence Management: Online/offline status tracking
Call Controls: Mute, speaker toggle, video toggle, camera switch, duration tracking
Automatic Reconnection: Built-in connection management with exponential backoff
ICE Management: Automatic ICE candidate buffering and exchange
Foldable Device Support: Detect fold state changes on Android devices
Cross-Platform: Android, iOS, Web, Linux, macOS, Windows
Professional Logging: Emoji-based console logging for easy debugging

Installation #

Add to your pubspec.yaml:

dependencies:
  nexacon_sdk: ^1.3.4

Install:

flutter pub get

Platform Requirements #

Platform	Minimum Version	Notes
Android	API 21 (Android 5.0)	Requires camera/audio permissions
iOS	12.0	Requires camera/audio permissions
Linux	Any	Works out of the box
macOS	10.14	Requires camera/audio entitlements
Web	Modern browsers	Requires WebRTC support
Windows	Any	Works out of the box

Platform Configuration #

Android #

Add to android/app/src/main/AndroidManifest.xml:

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.RECORD_AUDIO"/>
<uses-permission android:name="android.permission.CAMERA"/>
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>
<uses-permission android:name="android.permission.WAKE_LOCK"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT"/>

Set minimum SDK in android/app/build.gradle:

android {
    defaultConfig {
        minSdkVersion 21
    }
}

iOS #

Add to ios/Runner/Info.plist:

<key>NSCameraUsageDescription</key>
<string>Camera access is required for video calls</string>
<key>NSMicrophoneUsageDescription</key>
<string>Microphone access is required for audio calls</string>
<key>UIBackgroundModes</key>
<array>
  <string>audio</string>
  <string>voip</string>
</array>

Set minimum iOS version in ios/Podfile:

platform :ios, '12.0'

macOS #

Add to macos/Runner/DebugProfile.entitlements and Release.entitlements:

<key>com.apple.security.device.camera</key>
<true/>
<key>com.apple.security.device.microphone</key>
<true/>
<key>com.apple.security.network.client</key>
<true/>

Web, Linux, Windows #

No additional configuration required.

Quick Start — Outgoing Call #

Use NexaconSDK for the simplest possible integration:

import 'package:nexacon_sdk/nexacon_sdk.dart';

final sdk = NexaconSDK(
  apiKey: 'your_api_key',
  secretKey: 'your_secret_key',
);

// Set up callbacks
sdk.onCallStateChanged = (state) => print('📱 State: $state');
sdk.onCallEnded       = (reason) => print('📞 Ended: $reason');
sdk.onError           = (error)  => print('❌ Error: $error');

// Start an outgoing call — handles token, connection & signaling automatically
await sdk.startCall(
  to: '+255788811192',       // recipient
  username: '+255788811191', // your username
  audio: true,
  video: false,
);

// In-call controls
sdk.toggleMute(true);     // mute microphone
sdk.toggleSpeaker(true);  // enable speaker
sdk.toggleVideo(true);    // enable video
await sdk.switchCamera(); // switch front/back camera

// End call and release resources
await sdk.endCall();
await sdk.dispose();

Quick Start — Incoming Call #

Incoming calls can be handled via two paths:

Path 1: NX (app in foreground) #

Use acceptWhenReady() when the app is already open — it waits for the NX callInvitation signal:

import 'package:nexacon_sdk/nexacon_sdk.dart';

final sdk = NexaconSDK(
  apiKey: 'your_api_key',
  secretKey: 'your_secret_key',
);

// Set up callbacks
sdk.onCallStateChanged = (state) => print('📱 State: $state');
sdk.onIncomingCall     = (name)  => print('📞 Incoming from: $name');
sdk.onCallEnded        = (reason)=> print('📞 Ended: $reason');
sdk.onError            = (error) => print('❌ Error: $error');

// Initialize and automatically accept when NX signal arrives
await sdk.acceptWhenReady(
  username: '+255788811191',
  audio: true,
  video: false,
);

// End call and release resources
await sdk.endCall();
await sdk.dispose();

Path 2: Push Notification (app opened from FCM) #

Use acceptFromNotification() when the user opens the app from a push notification — the FCM payload already contains roomId and callerNxId:

// Called when user taps the FCM notification
await sdk.acceptFromNotification(
  username: '+255788811191',
  roomId: fcmData['room'],        // from FCM payload
  callerNxId: fcmData['caller'],  // from FCM payload (caller's phone/NX ID)
  callerName: fcmData['caller_name'],
  audio: true,
  video: false,
);

Advanced Usage #

For full low-level control, use NexaconClient directly.

Step 1: Initialize Client #

import 'package:nexacon_sdk/nexacon_sdk.dart';

final client = NexaconClient(
  apiKey: 'your_api_key',
  secretKey: 'your_secret_key',
  // baseUrl is optional — defaults to https://nxservice.quantumvision-tech.com/api/v1.0
);

Step 2: Generate NX Token #

final nxResponse = await client.auth.getNxToken(username: '+255788811191');

final nxtoken = nxResponse['token'];
final nxid    = nxResponse['jid'];
final wsUrl   = nxResponse['nxws'];

// IMPORTANT: Required to avoid 403 errors on subsequent API calls
client.setToken(nxtoken);

Step 3: Create CallManager #

final callManager = await client.createCallManager(
  nxtoken: nxtoken,
  nxid: nxid,
  wsUrl: wsUrl,
  name: 'Your Display Name',
  onCallStateChanged: (state) {
    if (state == CallState.connected) print('✅ Connected');
  },
  onIncomingCall: (callerName) => print('📞 Incoming: $callerName'),
  onCallEnded:    (reason)     => print('📞 Ended: $reason'),
  onError:        (error)      => print('❌ $error'),
);

Step 4: Make or Accept a Call #

// Outgoing call
await callManager.initiateCall(to: '+255788811192', audio: true, video: false);

// Accept incoming call
await callManager.acceptCall(audio: true, video: false);

// Reject incoming call
callManager.rejectCall();

// End current call
await callManager.endCall();

Step 5: In-Call Controls #

callManager.webrtcService?.toggleAudio(false);  // mute
callManager.webrtcService?.toggleAudio(true);   // unmute
callManager.webrtcService?.toggleVideo(false);  // disable video
callManager.webrtcService?.toggleVideo(true);   // enable video
callManager.webrtcService?.toggleSpeaker(true); // speaker on
await callManager.webrtcService?.switchCamera();

final duration = callManager.callDuration;
print('Duration: ${duration.inSeconds}s');

Step 6: Cleanup #

callManager.dispose();
client.close();

Real-Time Messaging #

final messagingManager = client.createMessagingManager();

// Receive messages
messagingManager.messageStream.listen((message) {
  print('💬 ${message['from']}: ${message['message']}');
});

// Send a message
messagingManager.sendMessage(to: 'recipient@example.com', message: 'Hello!');

// Typing indicator
messagingManager.sendTypingIndicator('recipient@example.com', isTyping: true);

// Read receipt
messagingManager.sendReadReceipt('recipient@example.com', 'msg_123');

// Presence (online/offline)
messagingManager.presenceStream.listen((presence) {
  final isOnline = presence['type'] == null || presence['type'] == 'available';
  print('User is ${isOnline ? 'online' : 'offline'}');
});

messagingManager.dispose();

Foldable Device Support #

final foldStateService = FoldStateService();

foldStateService.foldStateStream.listen((state) {
  switch (state) {
    case FoldState.flat:     print('Device is flat');
    case FoldState.folded:   print('Device is folded');
    case FoldState.halfOpen: print('Device is half open');
    case FoldState.unknown:  print('Fold state unknown');
  }
});

if (foldStateService.isFolded) {
  // Adjust UI for folded state
}

foldStateService.dispose();

Call States #

State	Description
`idle`	No active call
`calling`	Outgoing call in progress
`incoming`	Incoming call received
`connected`	Call connected
`ended`	Call ended

API Reference #

NexaconSDK (Simplified) #

NexaconSDK({required String apiKey, required String secretKey, String? baseUrl})

Method	Description
`initialize({required username, name})`	Connect to signaling without dialing — use for incoming calls
`startCall({required to, required username, name, audio, video})`	Start outgoing call — handles everything internally
`acceptWhenReady({required username, name, audio, video, timeout})`	Initialize and auto-accept when NX signal arrives (foreground)
`acceptFromNotification({required username, roomId, callerNxId, callerName, name, audio, video})`	Accept using FCM/push payload data (background)
`acceptCall({audio, video})`	Accept an incoming call (must be in `incoming` state)
`rejectCall()`	Reject an incoming call
`endCall()`	End the current call
`toggleMute(bool muted)`	Toggle microphone
`toggleSpeaker(bool enabled)`	Toggle speaker
`toggleVideo(bool enabled)`	Toggle video
`switchCamera()`	Switch front/back camera
`dispose()`	Cleanup all resources

Property	Type	Description
`callDuration`	`Duration`	Current call duration

Callback	Signature	Description
`onCallStateChanged`	`Function(CallState)`	Call state updates
`onIncomingCall`	`Function(String)`	Incoming call received
`onCallEnded`	`Function(String)`	Call ended with reason
`onError`	`Function(String)`	Error occurred
`onLocalStream`	`Function()`	Local video stream ready
`onRemoteStream`	`Function()`	Remote video stream ready

NexaconClient (Advanced) #

NexaconClient({required String apiKey, required String secretKey, String? baseUrl})

Method	Description
`auth.getNxToken({required username})`	Generate NX token
`setToken(String token)`	Set NX token for API auth
`createCallManager({...})`	Create a CallManager instance
`createMessagingManager()`	Create a MessagingManager instance
`close()`	Close the client

CallManager #

Method	Description
`initiateCall({required to, audio, video})`	Start outgoing call
`acceptCall({audio, video})`	Accept incoming call
`rejectCall()`	Reject incoming call
`endCall()`	End current call
`dispose()`	Cleanup resources

MessagingManager #

Stream	Description
`messageStream`	Incoming messages
`typingStream`	Typing indicators
`readReceiptStream`	Read receipts
`presenceStream`	Presence changes

Method	Description
`sendMessage({required to, required message})`	Send a message
`sendTypingIndicator(to, {isTyping})`	Send typing status
`sendReadReceipt(to, messageId)`	Send read receipt
`dispose()`	Cleanup

Troubleshooting #

403 Error on Call Initiation #

Cause: NX token not set on the client.

Fix (Advanced API only — NexaconSDK handles this automatically):

client.setToken(nxtoken); // Must be called after getNxToken()

NX Connection Timeout #

Cause: WebSocket URL uses https:// instead of wss://.

Fix: NexaconSDK converts this automatically. If using NexaconClient directly, ensure wsUrl starts with wss://.

Camera / Microphone Not Working #

Android: Ensure permissions are in AndroidManifest.xml and granted at runtime
iOS: Ensure keys are in Info.plist
Web: App must be served over HTTPS (WebRTC requirement)

Call Stuck in "Calling" #

Ensure the callee is online with the SDK initialized
Calls time out after 60 seconds if not accepted

Second Call Auto-Ends After Acceptance #

Cause (pre-1.3.4): When the NX connection is re-established for a second call, the server replays queued messages from the previous session — including the old call_end signal. Two bugs compounded this:

The CallManager NX subscription was never cancelled on call end — an orphaned subscription could process stale signals after internal state was reset to idle.
There was no room ID validation — any call_end was processed unconditionally.

Fixed in v1.3.4:

The StreamSubscription is now stored and immediately cancelled in _endCall(), making the old CallManager permanently deaf after a call ends.
Every non-invitation signal is validated against _currentRoomId — mismatched room IDs are silently dropped.
NexaconSDK.endCall() nulls the internal _callManager so the next call always gets a completely fresh instance.

Required app-side guard (still needed even with 1.3.4):

onOtherUserLeft: () {
  // Only end call if the WebRTC peer actually joined.
  // Guards against any residual state on the app layer.
  if (!_isOtherUserConnected) return;
  _endCall();
},

Console Log Reference #

Emoji	Meaning
🔐	Authentication
📞	Call operations
📡	Signaling / WebRTC
✅	Success
❌	Error
⚠️	Warning

Getting Help #

License #

MIT License — see LICENSE for details.

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