Apple Login Integration (Unreal + Beamable)¶

This document describes how to integrate Apple / Game Center login in an Unreal Engine project and how Login and Attach federation flows work when linking Apple accounts to Beamable players.

Overview¶

Apple authentication is handled on the client using Unreal’s OnlineSubsystemIOS, while account linking and authentication are handled on the server using Beamable Federation.

High-level flow:

Authenticate the player using Game Center
Retrieve the Apple UserId
Send the UserId to a Beamable Federation Microservice
Beamable either logs the player in or attaches the Apple identity

Prerequisites¶

Unreal iOS Setup¶

Follow Unreal’s official documentation to configure iOS builds:

https://dev.epicgames.com/documentation/en-us/unreal-engine/setting-up-an-unreal-engine-project-for-ios

Apple Developer Configuration¶

Enable the following capabilities in your Apple Developer project:

Game Center
Sign in with Apple

Apple documentation: https://developer.apple.com/documentation/gamekit/initializing-and-configuring-game-center

If these capabilities are not enabled, Apple authentication may silently fail on device.

Enabling OnlineSubsystemIOS¶

Apple login relies on Unreal’s OnlineSubsystemIOS plugin.

Enable it via Edit → Plugins or by copying it from the Engine plugins folder.

API reference: https://dev.epicgames.com/documentation/en-us/unreal-engine/API/PluginIndex/OnlineSubsystemIOS

Build.cs Configuration¶

if (Target.Platform == UnrealTargetPlatform.IOS)
{
    DynamicallyLoadedModuleNames.Add("OnlineSubsystemIOS");
}

The client authenticates with Game Center and retrieves a unique Apple UserId.

Responsibilities¶

Trigger Game Center login
Retrieve the Apple UserId
Expose the result to Blueprint

Required Functions¶

Login
GetUserId

Reference implementation: https://github.com/beamable/UnrealSDK/tree/main/Plugins/BEAMPROJ_BeamFarm/Source/BEAMPROJ_BeamFarm

Federation Concept (Beamable)¶

Beamable Federation allows external identity providers to authenticate or link accounts.

For Apple integration:

The Apple UserId is used as the federation token
The token uniquely identifies the Apple user
Beamable uses it to authenticate or attach the identity

Federation reference: user-reference/federation/federated-login

Apple Federation Microservice¶

Federation Identifier¶

[FederationId("gamecenter")]
public class GameCenterFederation : IFederationId
{
}

async Promise<FederatedAuthenticationResponse>
    IFederatedLogin<GameCenterFederation>.Authenticate(
        string token,
        string _,
        string __)
{
    return new FederatedAuthenticationResponse()
    {
        user_id = token
    };
}

Purpose: Authenticate a player who has already linked Apple.

Client:

Game Center Login
Retrieve Game Center UserId
Call Federated Login

Server:

Finds account linked to Apple UserId
Logs player in

Result:

Player authenticated

Attach Flow (First-Time Link)¶

Purpose: Link Apple to an existing account.

Client:

Apple Login
Retrieve Apple UserId
Call Attach – Federated Identity

Server:

Links Apple UserId to current account

Result:

Apple identity attached
Progress preserved

Client Blueprint¶

Trigger Apple Login
Retrieve UserId
Call Attach or Login
Handle success or failure

Required Files for Game Center on iOS¶

Two additional files must be present in the project for Game Center to work correctly on iOS.

SSL Certificate (`cacert.pem`)¶

Beamable uses secure socket connections on iOS, and the OS requires a trusted CA certificate bundle to validate them. Without this file, Beamable network calls will fail silently on device.

Locate the certificate file bundled with the engine:

\Epic Games\UE_5.6\Engine\Content\Certificates\ThirdParty\cacert.pem

Copy it into a folder named Certificates inside your project's Source folder:
```
<ProjectRoot>/Source/Certificates/cacert.pem
```

Unreal will include this file in the iOS bundle, allowing Beamable to establish trusted connections at runtime.

Game Center Entitlements (`GameCenter.entitlements`)¶

Unreal must be told about the entitlements file so it can embed the correct Apple capabilities (Game Center and Sign in with Apple) during the build and signing process.

In your project's iOS build settings, verify that the Additional Plist Data or equivalent entitlements path is pointing to a file named GameCenter.entitlements located at the root of the project:

<ProjectRoot>/GameCenter.entitlements

This file must be referenced in the project settings so that Unreal includes it during code signing. Without it, Apple capabilities such as Game Center will not be active in the signed build, and authentication will fail.