Deep Linking for Mobile Apps (Flutter, iOS, Android, React Native)

import 'package:app_links/app_links.dart';

final _appLinks = AppLinks();

Future<void> initDeepLinkListener() async {
  // Handles the link that launched the app (cold start)
  final initialUri = await _appLinks.getInitialLink();
  _handleIncomingLink(initialUri);

  // Handles links received while the app is already running
  _appLinks.uriLinkStream.listen(_handleIncomingLink);
}

void _handleIncomingLink(Uri? uri) {
  if (uri == null) return;
  final refId = uri.queryParameters['fpr'];
  if (refId != null) {
    storeReferralId(refId); // persist with shared_preferences / secure storage
  }
}

func scene(_ scene: UIScene, continue userActivity: NSUserActivity) {
    guard userActivity.activityType == NSUserActivityTypeBrowsingWeb,
          let url = userActivity.webpageURL,
          let components = URLComponents(url: url, resolvingAgainstBaseURL: false) else { return }

    if let refId = components.queryItems?.first(where: { $0.name == "fpr" })?.value {
        UserDefaults.standard.set(refId, forKey: "fpr_ref_id")
    }
}

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    handleIntent(intent)
}

override fun onNewIntent(intent: Intent) {
    super.onNewIntent(intent)
    handleIntent(intent)
}

private fun handleIntent(intent: Intent) {
    val data: Uri? = intent.data
    val refId = data?.getQueryParameter("fpr")
    if (refId != null) {
        getSharedPreferences("fpr", MODE_PRIVATE).edit()
            .putString("fpr_ref_id", refId)
            .apply()
    }
}

import { Linking } from 'react-native';
import AsyncStorage from '@react-native-async-storage/async-storage';

function extractRefId(url) {
  if (!url) return null;
  const { queryParams } = Linking.parse(url); // or new URL(url).searchParams
  return queryParams?.fpr ?? null;
}

// Cold start
Linking.getInitialURL().then((url) => {
  const refId = extractRefId(url);
  if (refId) AsyncStorage.setItem('fpr_ref_id', refId);
});

// While app is running
Linking.addEventListener('url', ({ url }) => {
  const refId = extractRefId(url);
  if (refId) AsyncStorage.setItem('fpr_ref_id', refId);
});