无法获得一个小部件组件的链接 UE4

Question

我有一个具有HexCell类的角色，我给他添加了一个具有HexWidget类的widget组件，然后我试图获取一个链接到widget组件，但没有任何效果。我尝试了许多解决方案，但都不奏效。如何获取小组件类的引用？

class BATTLETECH_API UHexWidget : public UUserWidget
{
    GENERATED_BODY()

};





class BATTLETECH_API AHexCell : public AActor
{
    GENERATED_BODY()

public: 
    // Sets default values for this actor's properties
    AHexCell();

    UPROPERTY(VisibleAnywhere, Category="Grid Setup")
    UHexWidget* Widget;


protected:
    // Called when the game starts or when spawned
    virtual void BeginPlay() override;



};

void AHexCell::BeginPlay()
{
    Super::BeginPlay();

    1 // the code compiles without errors, but the engine crushed if start
    Widget = Cast<UHexWidget>(GetOwner()->FindComponentByClass(UHexWidget::StaticClass()));

    2 // the code compiles without errors and the scene starts, but the link remains empty
    Widget = Cast<UHexWidget>(this->FindComponentByClass(UHexWidget::StaticClass()));

    3 //note: see reference to function template instantiation 'T *AActor::FindComponentByClass<UHexWidget>(void) const' being compiled
    Widget = GetOwner()->FindComponentByClass<UHexWidget>();
    Widget = Cast<UHexWidget>(this->FindComponentByClass<UHexWidget>());
    Widget = Cast<UHexWidget>(GetOwner()->FindComponentByClass<UHexWidget>());


}

Answer 1

这不能工作的原因有很多。

1. AHexCell 实例没有所有者（它是一个演员，很可能没有所有者，除非被玩家控制器拥有）。
2. AHexCell 没有组件 UHexWidget 而且很可能永远不会有：UHexWidget是一个。UUserWidget 该类没有继承 UActorComponent
3. 这是错的，因为1)和2)

你需要做的（除了一些OOP和虚幻引擎的研究之外）是 。

class BATTLETECH_API AHexCell : public AActor
{
    GENERATED_BODY()

public: 
    // Sets default values for this actor's properties
    AHexCell();


    UPROPERTY(VisibleAnywhere, Category="Components")
    UWidgetComponent* widgetComp;

    UPROPERTY(VisibleAnywhere, Category="Grid Setup")
    UHexWidget* Widget;


protected:
    // Called when the game starts or when spawned
    virtual void BeginPlay() override;

};


AHexCell::AHexCell()
{
   // spawn a widget component 
   widgetComp = createDefaultSubObject<UWidgetComponent>("widgetComponent");
   // or get it via FindComponent
   // widgetComp = FindComponentByClass<UWidgetComponent>();
}


AHexCell::BeginPlay()
{
    Super::BeginPlay();
    // check if your pointer is valid before calling functions on it
    if(widgetComp != nullptr)
         Widget = Cast<UHexWidget>(widgetComp->GetUserWidgetObject());
}