SDK Quickstart (Flutter)

Integrate Helium into your Flutter App

Background

Get set up with the Helium SDK for Flutter. Reach out over your Helium slack channel or email [e-mail] for any questions.

The Helium Flutter SDK currently supports iOS only. Android support is expected mid- to late-November.

Installation

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: ^3.0.12

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

In your app’s initialization code (typically in main.dart or your root widget), add the following to configure Helium and prepare your paywalls:

import 'package:helium_flutter/helium_flutter.dart';

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

  final heliumFlutter = HeliumFlutter();
  await heliumFlutter.initialize(
    apiKey: "<your-helium-api-key>",
//    fallbackPaywall: Text("your fallback view"),
//    fallbackBundleAssetPath: "fallback-bundle-xxxx-xx-xx.json",
  );

  runApp(const MyApp());
}

Including a fallback option is highly recommended. See the Fallbacks section on this page.

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.

purchaseDelegate · HeliumPurchaseDelegate?

(Optional) Delegate for handling your own purchase logic. If not provided, Helium will handle purchase logic for you.

fallbackPaywall · Widget?

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

customUserId · String?

(Optional) If set, 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 (e.g. an amplitude user id, or a custom user id from your own analytics service)

customUserTraits · Map<String, dynamic>?

(Optional) Pass in custom user traits to be used for targeting, personalization, and dynamic paywall content.

revenueCatAppUserId · String?

(Optional) RevenueCat ONLY. Supply RevenueCat appUserID here (and initialize RevenueCat before Helium initialize). You can also set this value outside of initialize: HeliumFlutter().setRevenueCatAppUserId(await Purchases.appUserID)

fallbackBundleAssetPath · String?

(Optional) Path to fallback bundle. See Fallbacks section.

paywallLoadingConfig · HeliumPaywallLoadingConfig?

(Optional) Set loading budget in seconds and whether to even show a loading state. This can be done per trigger.

final paywallLoadingConfig = HeliumPaywallLoadingConfig(
  loadingBudget: 5, // after 5 seconds, show fallback instead
  perTriggerLoadingConfig: {
    "onboarding": TriggerLoadingConfig(useLoadingState: false),
    "from_menu": TriggerLoadingConfig(useLoadingState: true, loadingBudget: 2),
  }
);

Custom User ID and Custom User Traits

You can set a custom user ID and custom user traits with the initialize method or by calling:

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

Set these values before or during initialize to ensure consistency in analytics events and for the best experimentation results.

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.

After initialization, you can check the status of the paywalls download:

String downloadStatus = await heliumFlutter.getDownloadStatus() ?? 'Unknown';

The download status will be one of the following:

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

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

Presenting Paywalls

You must have a trigger and workflow configured in the dashboard in order to show a paywall.

There are two ways to show a Helium paywall in your Flutter app.

1. Show it as a full-screen modal (recommended)

You can present a paywall programmatically using the presentUpsell method:

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 can also pass in event handlers and custom paywall traits directly to presentUpsell:

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}');
    },
  ),
  customPaywallTraits: {
    "has_seen_intro_video": true,
  }
);

2. Via Widget Integration

You can use the HeliumFlutter.getUpsellWidget method to embed a paywall directly in your widget tree:

class ExamplePageWithEmbeddedPaywall extends StatelessWidget {
  const ExamplePageWithEmbeddedPaywall({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: HeliumFlutter().getUpsellWidget(trigger: 'insert-trigger-here'),
    );
  }
}

You will have to handle your own dismissal in this case. You can do so by passing in PaywallEventHandlers and using the onDismissed handler.

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

Helium Events

To handle various paywall-related events, implement HeliumCallbacks and pass 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}');
  }
}

Handling Purchases

By default, Helium will handle purchase logic for you. If you want a custom implementation, you’ll want to implement HeliumPurchaseDelegate and pass that into initialize.

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

  Future<bool> restorePurchases();
}

Basic Implementation

Here’s a basic (incomplete) implementation of HeliumPurchaseDelegate:

import 'package:helium_flutter/helium_flutter.dart';
import 'dart:developer';

class PaymentCallbacks implements HeliumCallbacks {
  @override
  Future<HeliumPurchaseResult> makePurchase(String productId) async {
    log('makePurchase: $productId');
    // Implement your purchase logic here
    return HeliumPurchaseResult(status: HeliumTransactionStatus.purchased);
  }

  @override
  Future<bool> restorePurchases() async {
    log('restorePurchases called');
    // Implement your restore logic here
    return true;
  }
}

RevenueCat Implementation Example

import 'package:helium_flutter/helium_flutter.dart';
import 'package:purchases_flutter/purchases_flutter.dart';
import 'dart:developer';

class RevenueCatCallbacks implements HeliumCallbacks {
  @override
  Future<HeliumPurchaseResult> makePurchase(String productId) async {
    try {
      log('RevenueCat making purchase: $productId');
      final offerings = await Purchases.getOfferings();

      Package? packageToPurchase;

      // Search all offerings for package
      for (var offering in offerings.all.values) {
        for (var package in offering.availablePackages) {
          if (package.storeProduct.identifier == productId) {
            packageToPurchase = package;
            break;
          }
        }
        if (packageToPurchase != null) break;
      }

      CustomerInfo? customerInfo;
      if (packageToPurchase == null) {
        final fetchedProducts = await Purchases.getProducts([productId]);
        if (fetchedProducts.isEmpty) {
          return HeliumPurchaseResult(
              status: HeliumTransactionStatus.failed,
              error: 'Product not found in any offering and could not be retrieved: $productId'
          );
        } else {
          customerInfo = await Purchases.purchaseStoreProduct(fetchedProducts.first);
        }
      } else {
        customerInfo = await Purchases.purchasePackage(packageToPurchase);
      }

      // Check if the purchase was successful by looking at entitlements
      if (customerInfo.entitlements.active.isNotEmpty) {
        return HeliumPurchaseResult(status: HeliumTransactionStatus.purchased);
      } else {
        return HeliumPurchaseResult(status: HeliumTransactionStatus.failed);
      }
    } catch (e) {
      log('RevenueCat purchase error: $e');
      if (e is PurchasesErrorCode) {
        if (e == PurchasesErrorCode.purchaseCancelledError) {
          return HeliumPurchaseResult(status: HeliumTransactionStatus.cancelled);
        } else if (e == PurchasesErrorCode.paymentPendingError) {
          return HeliumPurchaseResult(status: HeliumTransactionStatus.pending);
        }
      }
      return HeliumPurchaseResult(
          status: HeliumTransactionStatus.failed,
          error: 'RevenueCat purchase error: ${(e as PlatformException?)?.message ?? "Unknown error"}'
      );
    }
  }

  @override
  Future<bool> restorePurchases() async {
    try {
      log('RevenueCat restoring purchases');
      final restoredInfo = await Purchases.restorePurchases();
      return restoredInfo.entitlements.active.isNotEmpty;
    } catch (e) {
      log('RevenueCat restore error: $e');
      return false;
    }
  }
}

Checking Subscription Status & Entitlements

Use these methods to check current user subscription status.

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

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

Example

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

Fallbacks

The Flutter SDK currently has two fallback options - 1) Fallback bundle and 2) a fallback view. Fallback situations should be quite rare, but to be safe, it is highly recommended that you implement a fallback bundle or custom fallback view.