UnrealEngine 4: dynamic load UMG from c++

gistfile1.cpp

// Fill out your copyright notice in the Description page of Project Settings.


UCLASS()
class HOPETOWERDEFENSE_API AHopePlayerController : public APlayerController
{
	//GENERATED_BODY()
	GENERATED_UCLASS_BODY()
public:
	//AHopePlayerController(const FObjectInitializer& ObjectInitializer);
	virtual ~AHopePlayerController();
public:
	virtual void BeginPlay() override;
	

	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = UI)
	TSubclassOf<UGameWidget> WidgetClass;
	UPROPERTY()
	UGameWidget* WidgetInstance;
};



AHopePlayerController::AHopePlayerController(const FObjectInitializer& ObjectInitializer)
	: Super(ObjectInitializer)

{
  //Must put in constructor
	ConstructorHelpers::FClassFinder<UGameWidget> PutNameHere(TEXT("/Game/MyUMG"));
	if (PutNameHere.Class) {
		WidgetClass = PutNameHere.Class;
	}
}



void AHopePlayerController::BeginPlay()
{
	Super::BeginPlay();
	if (WidgetClass) {
		if (!WidgetInstance) {
			WidgetInstance = CreateWidget<UGameWidget>(this, WidgetClass);
			UImage* image = NewObject<UImage>(UImage::StaticClass());
			image->SetVisibility(ESlateVisibility::Visible);
			UPanelWidget* rootPanel = (UPanelWidget*)WidgetInstance->GetRootWidget();
			//UPanelWidget* rootPanel = (UPanelWidget*)WidgetInstance->GetWidgetFromName(TEXT("RootCanvasPanel"));
			rootPanel->AddChild(image);
			UCanvasPanelSlot* canvasPanelSlot = (UCanvasPanelSlot*)image->Slot;
			auto slot = image->Slot;
			canvasPanelSlot->SetPosition(FVector2D(100, 100));
		}
	}
	if (!WidgetInstance->GetIsVisible())
	{
		WidgetInstance->AddToViewport();
	}
}