SK2ForDotNet

StoreKit 2 wrapper for .NET iOS projects. Bridges Apple's Swift-only StoreKit 2 APIs to .NET via @objc-compatible interfaces compiled as an .xcframework.

Why?

.NET for iOS has no StoreKit 2 bindings because StoreKit 2 is a Swift-only API. Apple removed StoreKit 1 from the Xcode 26 SDK, so .NET iOS projects need a bridge to continue supporting in-app purchases.

This library provides that bridge: a small Swift wrapper compiled into an .xcframework, with a .NET binding project on top.

Requirements

• .NET 10 iOS (net10.0-ios)
• iOS 15.0+ (required by StoreKit 2)
• Xcode 26+ (for building the xcframework from source)

Installation

Project Reference

Clone the repo and add a project reference to your iOS .csproj:

<ProjectReference Include="path/to/StoreKit2ForDotNet/binding/SK2ForDotNet.Binding/SK2ForDotNet.Binding.csproj" />

You also need to add the native framework reference in your iOS project:

<NativeReference Include="path/to/StoreKit2ForDotNet/binding/SK2ForDotNet.Binding/SK2ForDotNet.xcframework">
  <Kind>Framework</Kind>
  <SmartLink>false</SmartLink>
  <Frameworks>StoreKit Foundation</Frameworks>
</NativeReference>

Your project must also link with the Swift standard libraries. If you already have this (e.g. for Firebase), no changes needed. Otherwise add this target to your .csproj:

<Target Name="LinkWithSwift" DependsOnTargets="_ParseBundlerArguments;_DetectSdkLocations"
        BeforeTargets="_LinkNativeExecutable">
  <PropertyGroup>
    <_SwiftPlatform Condition="$(RuntimeIdentifier.StartsWith('iossimulator-'))">iphonesimulator</_SwiftPlatform>
    <_SwiftPlatform Condition="$(RuntimeIdentifier.StartsWith('ios-'))">iphoneos</_SwiftPlatform>
  </PropertyGroup>
  <ItemGroup>
    <_CustomLinkFlags Include="-L" />
    <_CustomLinkFlags Include="/usr/lib/swift" />
    <_CustomLinkFlags Include="-L" />
    <_CustomLinkFlags Include="$(_SdkDevPath)/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/$(_SwiftPlatform)" />
    <_CustomLinkFlags Include="-Wl,-rpath" />
    <_CustomLinkFlags Include="-Wl,/usr/lib/swift" />
  </ItemGroup>
</Target>

Usage

1. Create the wrapper and set the delegate

using SK2ForDotNet;

public class MyBillingService : SK2WrapperDelegate
{
    private readonly SK2Wrapper _wrapper;

    public MyBillingService()
    {
        _wrapper = new SK2Wrapper();
        _wrapper.WeakDelegate = this;
    }

2. Initialize (loads current entitlements and starts observing transactions)

    public void Start()
    {
        _wrapper.Initialize();
    }

3. Receive entitlement updates via the delegate

    public override void DidUpdateEntitlements(SK2Wrapper wrapper, SK2TransactionInfo[] transactions)
    {
        // Called on init and whenever entitlements change
        foreach (var tx in transactions)
        {
            Console.WriteLine($"Owned: {tx.ProductId} (type: {tx.ProductType})");
        }
    }

    public override void DidEncounterError(SK2Wrapper wrapper, NSError error)
    {
        Console.WriteLine($"Error: {error.LocalizedDescription}");
    }

4. Purchase a product

    public void Purchase(string productId)
    {
        _wrapper.Purchase(productId, (result, transaction, error) =>
        {
            switch (result)
            {
                case SK2PurchaseResultType.Success:
                    // Purchase succeeded, entitlements will also update via delegate
                    break;
                case SK2PurchaseResultType.UserCancelled:
                    break;
                case SK2PurchaseResultType.Pending:
                    // Ask to Buy or deferred
                    break;
                case SK2PurchaseResultType.Failed:
                    Console.WriteLine($"Failed: {error?.LocalizedDescription}");
                    break;
            }
        });
    }

5. Fetch product info (optional)

    public void LoadProducts(string[] productIds)
    {
        _wrapper.FetchProducts(productIds, (products, error) =>
        {
            if (products != null)
            {
                foreach (var p in products)
                    Console.WriteLine($"{p.DisplayName}: {p.DisplayPrice}");
            }
        });
    }
}

API Reference

SK2Wrapper

Method	Description
Initialize()	Loads current entitlements and starts observing Transaction.updates. Results arrive via DidUpdateEntitlements.
Purchase(productId, completion)	Fetches the product and launches the App Store payment sheet. Completion returns SK2PurchaseResultType.
FetchProducts(productIds, completion)	Fetches product metadata (name, price, type) from the App Store.

SK2WrapperDelegate

Method	Description
DidUpdateEntitlements(wrapper, transactions)	Called with the full list of active entitlements. Fires on init and on every transaction update.
DidEncounterError(wrapper, error)	Optional. Called when an error occurs.

SK2TransactionInfo

Property	Type	Description
ProductId	string	The product identifier
TransactionId	long	Unique transaction ID
OriginalTransactionId	long	Original transaction ID (for renewals)
PurchaseDate	NSDate	When the purchase was made
ProductType	string	"nonConsumable", "consumable", "autoRenewable", "nonRenewable"
ExpirationDate	NSDate?	Subscription expiration (nil for non-subscriptions)
IsRevoked	bool	Whether the transaction has been revoked

SK2ProductInfo

Property	Type	Description
ProductId	string	The product identifier
DisplayName	string	Localized product name
DisplayPrice	string	Localized price string (e.g. "$4.99")
Price	NSDecimalNumber	Numeric price
ProductType	string	Product type string

SK2PurchaseResultType

Value	Description
Success	Purchase completed and verified
UserCancelled	User dismissed the payment sheet
Pending	Purchase requires approval (Ask to Buy)
Failed	Purchase failed

Building the xcframework from source

The repo includes a prebuilt .xcframework. To rebuild from Swift source:

./scripts/build-xcframework.sh

This requires Xcode 26+ and builds for both iOS device (arm64) and simulator (arm64 + x86_64).

Architecture

Swift (StoreKit 2)  -->  @objc interfaces  -->  .xcframework  -->  .NET binding  -->  your C# code

The Swift layer wraps StoreKit 2's async APIs behind @objc-compatible delegate and completion-block patterns. The .NET binding project provides C# types that map to the ObjC interface. Your code interacts only with the C# types.

License

MIT