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Writing files to Player Data Storage

Before you can retrieve per-user data from Player Data Storage, you need to store data first.

Writing a file to Player Data Storage​

To upload data to Player Data Storage, first get the user cloud interface:

#include "OnlineSubsystem.h"
#include "OnlineSubsystemUtils.h"

// ...
IOnlineSubsystem* Subsystem = Online::GetSubsystem(this->GetWorld());
IOnlineUserCloudPtr UserCloud = Subsystem->GetUserCloudInterface();

Register the event handler so you know when data writing has completed. WriteUserDataDelegateHandle is declared as an FDelegateHandle.

this->WriteUserDataDelegateHandle =
    UserCloud->AddOnWriteUserFileCompleteDelegate_Handle(FOnWriteUserFileComplete::FDelegate::CreateUObject(
        this,
        &UMyClass::HandleWriteUserFileComplete));

Then call WriteUserFile with the content that you want to write:

TArray<uint8> FileData;

// If you wanted to write a Save Game to Player Data Storage, you could
// populate FileData from a USaveGame* instance:
UGameplayStatics::SaveGameToMemory(SaveGame, FileData);

UserCloud->WriteUserFile(
    *LocalUserId,
    FileName,
    FileData);

When the callback fires, you'll want to handle any errors (check bWasSuccessful), and then deregister the event handler:

void UMyClass::HandleWriteUserFileComplete(
    bool bWasSuccessful,
    FUniqueNetId UserId,
    const FString &FileName)
{
    // Deregister the event handler.
    IOnlineSubsystem *Subsystem = Online::GetSubsystem(this->GetWorld());
    IOnlineUserCloudPtr UserCloud = Subsystem->GetUserCloudInterface();

    UserCloud->ClearOnWriteUserFileCompleteDelegate_Handle(this->WriteUserDataDelegateHandle);
    this->WriteUserDataDelegateHandle.Reset();

    if (!bWasSuccessful)
    {
        // Data write didn't succeed, return error.
    }
    else 
    {
        // Successfully wrote data.
    }
}