Unresolved external symbol when trying to add widget to the viewport

Development Programming & Scripting
1

I want to add widget to the viewport using c++, but I’m getting error:

Act_31.cpp.obj : error LNK2019: unresolved external symbol “__declspec(dllimport) private: static class UClass * __cdecl UUserWidget::GetPrivateStaticClass(void)” (_imp?GetPrivateStaticClass@UUserWidget@@CAPEAVUClass@@anonymous_user_9674a66c) referenced in function “private: void __cdecl AAct_31::GameCicle(void)” (?GameCicle@AAct_31@@AEAAXXZ)

What I am doing wrong?

.h

class UUserWidget;

UCLASS()
class HOME_API AAct_31 : public AActor
{
    GENERATED_BODY()

    UFUNCTION() void GameCicle();

public: 
    AAct_31();

    class UUserWidget* blackLinesWidget;
    class UClass* blackLinesWidgetClass;

    virtual void Tick(float DeltaTime) override;

protected:
    virtual void BeginPlay() override;
};

.cpp

void AAct_31::Tick(float DeltaTime)
{
    Super::Tick(DeltaTime);
    GameCicle();
}

void AAct_31::GameCicle()
{
    FStringClassReference blackLinesWidgeClasstRef(TEXT("/Game/Blueprints/UI/blackLines"));
    blackLinesWidgetClass = blackLinesWidgeClasstRef.TryLoadClass<UUserWidget>(); // Error

    if (blackLinesWidgetClass)
    {
        blackLinesWidget = CreateWidget<UUserWidget>(this->GetGameInstance(), blackLinesWidgetClass);
        if (blackLinesWidget)
            blackLinesWidget->AddToViewport();
    }   
}
3 Likes
2

Hi,

Hope this helps.

You will have to go to your Build.cs file and add “UMG” to the PublicDependencyModulesNames.

Also add “Slate” and “SlateCore” to PrivateDependencyModuleNames.

It should look like this:

298004-buildcs.jpg
298004-buildcs.jpg1286×331 44.1 KB

13 Likes
3

It helped, thank you very much! But where could I find it? There is no documentation about it

4

You’re welcome. Yeah it’s in the docs :

1 Like
5

PS. You don’t need to forward declare class UUserWidget above UCLASS() because you’ve already done so in the public section of your header.