Authentication with Epic Games

Before we implement the Epic Games login method, let's first understand what it is and why it needs two nodes as compared to other login methods.

Basic Information

There are two parts of this authentication,

Persistent Auth - This is used to authenticate the user using existing credentials and hence will fail for the first time login.
Account Portal - This is used to launch the browser with the Epic Games login page and authenticate the user and then get the user's credentials.

This is the reason why we have two nodes for the Epic Games login method where the first node is used to login with Persistent Auth and if it fails, the second node is used to login with the Account Portal. If the login with the Account Portal is success, then the credentials will be saved by EOS SDK and the next time login should be silent.

Blueprint Implementation

The implementation of the Epic Games login method is quite simple. Here is an example of how you can do this:

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C++ Implementation

Basically, if the user has already logged in once before using the Account Portal, then the user can login using the Persistent Auth method. If the user has not logged in before, then the user has to login using the Account Portal. Which means we have to call the Persistent Auth method first and if it fails, then we have to call the Account Portal method.

Build.cs File

Add the following lines to your Build.cs file:

PrivateDependencyModuleNames.AddRange(new string[] { "OnlineSubsystem", "OnlineSubsystemUtils" });

This will add the required modules to your project and as EIK is already integrated, you don't need to add any other modules for this method.

Header File

#include "OnlineSubsystem.h"
#include "OnlineSubsystemUtils.h"
#include "Interfaces/OnlineIdentityInterface.h"
 
// Other stuff
 
public:
	// This function is used to login using already saved credentials, if the user has already logged in once before using the Account Portal.
	void LoginWithPersistentAuth();
	void LoginWithPersistentAuthCallback(int32 LocalUserNum, bool bWasSuccess, const FUniqueNetId& UserId, const FString& Error);
 
	// This function is used to login using the Account Portal
	void LoginWithAccountPortal();
	void LoginWithAccountPortalCallback(int32 LocalUserNum, bool bWasSuccess, const FUniqueNetId& UserId, const FString& Error);

Source File

void UMyGameInstanceSubsystem::LoginWithPersistentAuth()
{
	if(const IOnlineSubsystem *SubsystemRef = Online::GetSubsystem(GetWorld()))
	{
		if(const IOnlineIdentityPtr IdentityPointerRef = SubsystemRef->GetIdentityInterface())
		{
			FOnlineAccountCredentials AccountDetails;
			AccountDetails.Type = "eas_+_EIK_LCT_PersistentAuth_+_EIK_ECT_EPIC";
			IdentityPointerRef->OnLoginCompleteDelegates->AddUObject(this,&UMyGameInstanceSubsystem::LoginWithPersistentAuthCallback);
			IdentityPointerRef->Login(0,AccountDetails);
		}
	}
}
 
void UMyGameInstanceSubsystem::LoginWithPersistentAuthCallback(int32 LocalUserNum, bool bWasSuccess,
	const FUniqueNetId& UserId, const FString& Error)
{
	if(bWasSuccess)
	{
		UE_LOG(LogTemp, Warning, TEXT("LoginWithPersistentAuthCallback: Login was successful. UserID: %s"), *UserId.ToString());
	}
	else
	{
		UE_LOG(LogTemp, Error, TEXT("LoginWithPersistentAuthCallback: Login was not successful. Error: %s"), *Error);
		// Basically, the user has to login again with the Account Portal
		LoginWithAccountPortal();
	}
}
 
void UMyGameInstanceSubsystem::LoginWithAccountPortal()
{
	if(const IOnlineSubsystem *SubsystemRef = Online::GetSubsystem(GetWorld()))
	{
		if(const IOnlineIdentityPtr IdentityPointerRef = SubsystemRef->GetIdentityInterface())
		{
			FOnlineAccountCredentials AccountDetails;
			AccountDetails.Type = "eas_+_EIK_LCT_AccountPortal_+_EIK_ECT_EPIC";
			IdentityPointerRef->OnLoginCompleteDelegates->AddUObject(this,&UMyGameInstanceSubsystem::LoginWithAccountPortalCallback);
			IdentityPointerRef->Login(0,AccountDetails);
		}
	}
}
 
void UMyGameInstanceSubsystem::LoginWithAccountPortalCallback(int32 LocalUserNum, bool bWasSuccess,
	const FUniqueNetId& UserId, const FString& Error)
{
	if(bWasSuccess)
	{
		UE_LOG(LogTemp, Warning, TEXT("LoginWithAccountPortalCallback: Login was successful. UserID: %s"), *UserId.ToString());
	}
	else
	{
		UE_LOG(LogTemp, Error, TEXT("LoginWithAccountPortalCallback: Login was not successful. Error: %s"), *Error);
	}
}

Auto-Login Epic Games Store