SDK Quickstart (Flutter)

Integrate Helium into your Flutter App

To get a better understanding of how paywalls are served, visit here.

Present a Paywall

Install the SDK

The minimum version of Flutter supported by this SDK is 3.24.0.

To add the Helium package, run:

flutter pub add helium_flutter

Or if you prefer, you can add the helium_flutter package to your pubspec.yaml:

dependencies:
  helium_flutter: ^3.1.3

then run:

flutter pub get

Recommended - Make sure that Swift Package Manager support is enabled:

flutter upgrade
flutter config --enable-swift-package-manager

See this Flutter documentation for more details about Swift Package Manager.

You can still use Cocoapods for your dependencies if preferred. If you need to disable Swift Package Manager dependencies after having enabled it, refer to that same Flutter documentation.

iOS Settings

Helium requires iOS 15+. If your app already has a minimum of iOS 15 or higher, you’re all set. This can be specified in your ios/Podfile with:

platform :ios, '15.0'

If you still see errors related to minimum iOS version, consider updating to 15.0 or higher directly in the Xcode project.

Initialize Helium

Find your API key here. If you do not have a Helium account set up yet, you can still integrate but will not be able to show a real paywall.

In your app’s initialization code (typically in main.dart or your root widget):

import 'package:helium_flutter/helium_flutter.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();

  final heliumFlutter = HeliumFlutter();
  await heliumFlutter.initialize(
    apiKey: "<your-helium-api-key>",
  );

  runApp(const MyApp());
}

initialize · method

Show parameters

apiKey · string · required

You can create or retrieve your api key from Account Settings.

callbacks · HeliumCallbacks?

(Optional) Pass in a listener for paywall events. See the Helium Events section.

purchaseDelegate · HeliumPurchaseDelegate?

(Optional) Delegate for handling your own purchase logic. If not provided, Helium will handle purchase logic for you. See the RevenueCat and Custom Purchase Handling sections.

fallbackPaywall · Widget?

(Optional) A widget to display if paywall fails to display. See Fallback Paywalls section.

customUserId · String?

(Optional) A custom user id to use instead of Helium’s. We’ll use this id when forwarding to third party analytics services, so this can be used for attribution. See Identifying Users section.

customUserTraits · Map<String, dynamic>?

(Optional) Custom user traits to be used for targeting, personalization, and dynamic paywall content. See Identifying Users section.

revenueCatAppUserId · String?

(Optional) RevenueCat ONLY. Supply RevenueCat appUserID here (and initialize RevenueCat before Helium initialize). See RevenueCat section.

fallbackBundleAssetPath · String?

(Optional) Path to fallback bundle. See Fallback Paywalls section.

paywallLoadingConfig · HeliumPaywallLoadingConfig?

(Optional) Set loading budget in seconds and whether to show a loading state. See Fallback Paywalls section.

Show Your First Paywall 🎉

Set up a trigger and workflow in the dashboard to show your desired paywall. Create unique triggers for each location a paywall can show in your app! This provides more flexibility with paywall variation and experiments, allowing you to take full advantage of Helium.

Call presentUpsell wherever you want to show a full-screen paywall:

ElevatedButton(
  onPressed: () {
    final heliumFlutter = HeliumFlutter();
    heliumFlutter.presentUpsell(context: context, trigger: 'insert-trigger-here');
  },
  child: Text('Show Premium Features'),
),

Do not call presentUpsell in Widget build() as this can have unpredictable behavior.

You should now be able to see Helium paywalls in your app! Well done! 🎉

Looking for alternative presentation methods? Check out the guide on Ways to Show a Paywall.

Recommended Setup

Here are some common additional steps that you may want to consider.

Identifying Users

Identifying users is optional but can help with targeting and when forwarding events to external analytics platforms. If you are not sure, you probably do not need to identify your users.

Identify users as early as you can to maximize consistency in metrics and targeting. Ideally in your initialize call!

Set during initialize

await heliumFlutter.initialize(
  apiKey: "<your-helium-api-key>",
  customUserId: "your-custom-user-id",
  customUserTraits: {
    "exampleTrait": "value",
    "userType": "premium",
  },
);

await heliumFlutter.overrideUserId(
  newUserId: "your-custom-user-id",
  traits: {
    "exampleTrait": "value",
    "userType": "premium",
  },
);

Helium Events

Helium dispatches various events during paywall presentation and purchase flow. You can optionally handle these events in your mobile app. You can also configure Helium to forward them to your existing analytics provider.

PaywallEventHandlers

When displaying a paywall you can pass in event handlers to listen for select events:

HeliumFlutter().presentUpsell(
  trigger: 'my_paywall',
  context: context,
  eventHandlers: PaywallEventHandlers(
    onOpen: (event) {
      log('${event.type} - trigger: ${event.triggerName}');
    },
    onClose: (event) {
      log('${event.type} - trigger: ${event.triggerName}');
    },
    onDismissed: (event) {
      log('${event.type} - trigger: ${event.triggerName}');
    },
    onPurchaseSucceeded: (event) {
      log('${event.type} - trigger: ${event.triggerName}');
    },
    onAnyEvent: (event) {
      // A handler for all paywall-related events.
      // Note that if you have other handlers (i.e. onOpen) set up,
      // both that handler AND this one will fire during paywall open.
    },
  ),
);

Global Event Listener

You can also listen for all Helium events globally by implementing HeliumCallbacks and passing it to initialize:

abstract class HeliumCallbacks {
  Future<void> onPaywallEvent(HeliumPaywallEvent heliumPaywallEvent);
}

For example:

class LogCallbacks implements HeliumCallbacks {
  @override
  Future<void> onPaywallEvent(HeliumPaywallEvent heliumPaywallEvent) async {
    log('onPaywallEvent: ${heliumPaywallEvent.type} - trigger: ${heliumPaywallEvent.triggerName}');
  }
}

Then pass it to initialize:

await heliumFlutter.initialize(
  apiKey: "<your-helium-api-key>",
  callbacks: LogCallbacks(),
);

Fallback Paywalls

It is highly recommended that you set up “fallbacks” to handle the rare case when a paywall fails to display. Please follow this guide to do so.

Do this after you have a paywall created that you want to use in production.

Checking Subscription Status & Entitlements

Helium checks entitlements directly through the underlying app store (StoreKit on iOS, Google Play Billing on Android) and provides helper methods to make this easier. Consider checking entitlements to gate premium features.

If you have a backend server that manages user entitlements, you may have no use for these helpers.

All Entitlement Helper Methods

Called on a HeliumFlutter instance:

/// Checks if the user has any active subscription (including non-renewable)
Future<bool> hasAnyActiveSubscription();

/// Checks if the user has any entitlement
Future<bool> hasAnyEntitlement();

/// Checks if the user has an active entitlement for any product attached to
/// the paywall that will show for the provided trigger.
/// Returns `null` if not known (i.e. the paywall is not downloaded yet).
Future<bool?> hasEntitlementForPaywall(String trigger);

If you want to check entitlement status before presenting a paywall, here are a couple of ways to do so.

For paywalls that are user-initiated (e.g. “Upgrade to Premium”) and onboarding paywalls, checking entitled status is not recommended. Apps usually want to consistently show a paywall for these locations, and users can still “Restore Purchases” as needed.

Use dontShowIfAlreadyEntitled with presentUpsell

heliumFlutter.presentUpsell(
  trigger: 'my_paywall',
  context: context,
  dontShowIfAlreadyEntitled: true
);

final heliumFlutter = HeliumFlutter();
final hasActiveSubscription = await heliumFlutter.hasAnyActiveSubscription();
if (hasActiveSubscription) {
  featureGatedLogic(); // replace this with your logic
} else {
  heliumFlutter.presentUpsell(
    trigger: 'my_paywall',
    context: context,
    eventHandlers: PaywallEventHandlers(
      onPurchaseSucceeded: (event) {
        featureGatedLogic(); // replace this with your logic
      },
    )
  );
}

Advanced

RevenueCat

By default, Helium will handle purchases for you! This section is typically for users who already use RevenueCat in their app.

Helium integrates seamlessly with RevenueCat so you can continue to let RevenueCat handle your purchases and entitlements.

Install HeliumRevenueCat

Add the helium_revenuecat package alongside helium_flutter:

flutter pub add helium_revenuecat

Configure Helium to use RevenueCat for Purchases

Use the built-in RevenueCatPurchaseDelegate:

import 'package:helium_revenuecat/helium_revenuecat.dart';

final heliumFlutter = HeliumFlutter();
await heliumFlutter.initialize(
  apiKey: "<your-helium-api-key>",
  purchaseDelegate: RevenueCatPurchaseDelegate(),
);

Make sure to configure RevenueCat before initializing Helium.

RevenueCat appUserID

If you ever change the appUserID of a user, keep Helium in sync with:

HeliumFlutter().setRevenueCatAppUserId(await Purchases.appUserID);

Custom Purchase Handling

By default, Helium will handle purchases for you! This section is for those who want to implement custom purchase logic.

Implement HeliumPurchaseDelegate and pass it to initialize:

abstract class HeliumPurchaseDelegate {
  Future<HeliumPurchaseResult> makePurchase(String productId);

  Future<bool> restorePurchases();
}

Additional Features

For the full public API and detailed parameter documentation, see the inline docstrings in the SDK source. Import Helium in your project and use your IDE’s autocomplete or jump-to-definition to explore all available methods and types.

Checking Download Status

In most cases there is no need to check download status. Helium will display a loading indication if a paywall is presented before download has completed.

You can listen to the status of the paywalls download via a stream:

HeliumFlutter.downloadStatus.listen((status) {
  print('Download status: ${status.name}');
});

The download status will be one of the following:

• notDownloadedYet: The download has not been initiated.
• inProgress: The download is in progress.
• downloadSuccess: The download was successful.
• downloadFailure: The download failed.

You can also check if paywalls have been downloaded with await heliumFlutter.paywallsLoaded()

Hiding Paywalls Programmatically

You can programmatically hide paywalls using:

// Hide the current paywall
await HeliumFlutter().hideUpsell();

// Hide all currently displayed paywalls
await HeliumFlutter().hideAllUpsells();

Reset Helium

Reset Helium entirely so you can call initialize again, for example after changing user traits that can affect the paywalls a user might see via targeting.

await HeliumFlutter().resetHelium();