Unreal C++

Interfaces

Mistakes

When checking if an UObject implements an interface make sure to check against the

UInterface not the IInterfaceName

UINTERFACE(Blueprintable)
class UCursorSamplerInterface : public UInterface
{
  GENERATED_BODY()
};

class CURSORSAMPLER_API ICursorSamplerInterface
{
  GENERATED_BODY()
}

From other class

const bool bImplements = Sampler->Implements<ICursorSamplerInterface>();

C++ only Interfaces

Not used in blueprints and not implemented using blueprints

Unreal 5.5

I was having issue on Windows compiling an interface. The compiler was complaining about a missing definition on the .cpp file To solve this issue the functions should be declared as pure virtual

#pragma once

#include "CoreMinimal.h"
#include "AdapterDataTypes.h"
#include "UObject/Interface.h"
#include "EntityComponentDataInterface.generated.h"

// This class does not need to be modified.
UINTERFACE()
class UEntityComponentDataInterface : public UInterface
{
    GENERATED_BODY()
};

/**
 *
 */
class ENTANGLED_API IEntityComponentDataInterface
{
    GENERATED_BODY()

    // Add interface functions to this class. This is the class that will be inherited to implement this interface.
public:
    virtual bool Initialize() = 0;

    virtual const FBox& GetDataBounds() = 0; //!! Yes = 0
};

Headers

Declare function signature with pass by reference

UFUNCTION(BlueprintCallable)
  void AppendFieldDataByRef(UPARAM(ref) TArray<FEntangledExtended>& FieldArray, const FEntangledExtended& InValue);