Joining a lobby

You can join a lobby in one of two ways:

• You've previously searched for lobbies and found a result you want to join, or
• You've received a lobby ID from somewhere and parsed it

Joining a lobby

• C++
• Blueprints

First, get the online lobby interface:

#include "OnlineSubsystem.h"
#include "OnlineSubsystemUtils.h"
// If your project can't find this header, make sure you have installed the headers from here:
// https://src.redpoint.games/redpointgames/online-interfaces/
#include "OnlineLobbyInterface.h"

IOnlineSubsystem* Subsystem = Online::GetSubsystem(this->GetWorld());
TSharedPtr<IOnlineLobby, ESPMode::ThreadSafe> Lobby = Online::GetLobbyInterface(Subsystem);

Then, join the lobby:

if (!Lobby->ConnectLobby(
    *LocalUserId,
    *LobbyIdFromSearch,
    FOnLobbyCreateOrConnectComplete::CreateLambda([](
        const FOnlineError & Error,
        const FUniqueNetId & UserId,
        const TSharedPtr<class FOnlineLobby> & CreatedLobby)
    {
        if (Error.WasSuccessful())
        {
            // The lobby was joined successfully.
        }
        else
        {
            // Lobby could not be joined.
        }
    })))
{
    // Call failed to start.
}
// ...

Disconnecting from a lobby

• C++
• Blueprints

To disconnect from a lobby, you'll need the ID of the lobby you previously connected to and call DisconnectLobby like so:

if (!Lobby->DisconnectLobby(
    *LocalUserId,
    *LobbyIdFromPreviousConnectOrCreate,
    FOnLobbyOperationComplete::CreateLambda([](
        const FOnlineError& Error,
        const FUniqueNetId& UserId)
    {
        if (Error.WasSuccessful())
        {
            // Player has been disconnected from lobby.
        }
        else
        {
            // Could not disconnect from lobby.
        }
    })
))
{
    // Call failed to start.
}

Joining a lobby as party

• C++
• Blueprints

First, get the online lobby and party interfaces:

#include "OnlineSubsystem.h"
#include "OnlineSubsystemUtils.h"
// If your project can't find this header, make sure you have installed the headers from here:
// https://src.redpoint.games/redpointgames/online-interfaces/
#include "OnlineLobbyInterface.h"
#include "Interfaces/OnlinePartyInterface.h"

// ...

IOnlineSubsystem* Subsystem = Online::GetSubsystem(this->GetWorld());
TSharedPtr<IOnlineLobby, ESPMode::ThreadSafe> Lobby = Online::GetLobbyInterface(Subsystem);
IOnlinePartyPtr Party = Subsystem->GetPartyInterface();

Then, convert your LobbyId to an IOnlinePartyJoinInfoConstPtr:

FString JoinInfo = PartySystem->MakeJoinInfoJson(
    *InLocalUserId.GetUniqueNetId(), 
    InLobbyId);
if (!JoinInfo.IsEmpty()) 
{
    IOnlinePartyJoinInfoConstPtr JoinInfoPtr = PartySystem->MakeJoinInfoFromJson(JoinInfo);
    if (JoinInfoPtr.IsValid()) 
    {
        // JoinInfoPtr contains the OnlinePartyJoinInfo to pass into JoinParty().
    }
}

Once you have the resulting join info, you can proceed to Joining a party.