用UFUNCTION 宏 BlueprintCallable 声明蓝图可调用，还必须使用 BlueprintImplementableEvent 或 BlueprintNativeEvent 说明，而且函数不能为虚函数

如果不想蓝图重载，只是想使用 BlueprintCallable 以支持蓝图起到单纯的调用作用，可以通过将接口标记为 UINTERFACE(meta = (CannotImplementInterfaceInBlueprint)) 来解决

通过声明 virtual 虚函数，使得派生类可重载

ReactToTriggerInterface.h

#pragma once
#include "CoreMinimal.h"
#include "UObject/Interface.h"
#include "ReactToTriggerInterface.generated.h"
// 无需更改
// UINTERFACE类不是实际的接口；它是一个空白类，它的存在只是为了向虚幻引擎反射系统确保可见性。
UINTERFACE(MinimalAPI)
class UReactToTriggerInterface : public UInterface
	GENERATED_BODY()
//开头字母"U"必须改为"I"。
class TIPS_API IReactToTriggerInterface
	GENERATED_BODY()
public:
	// 纯虚函数，实现类必须实现接口
	virtual void ReactToTrigger_PureVirtual() = 0;
	// 虚函数，在接口本身的 .h 或 .cpp 文件中提供默认实现.实现类可覆盖
	virtual void ReactToTrigger_Virtual();
	//实现类可以在蓝图和C++中实现接口
	UFUNCTION(BlueprintCallable, BlueprintNativeEvent, Category="Trigger Reaction")
		void ReactToTrigger_NativeEvent1(int32 number);
	//实现类可以在蓝图和C++中实现接口
	UFUNCTION(BlueprintCallable, BlueprintNativeEvent, Category = "Trigger Reaction")
		bool ReactToTrigger_NativeEvent2(int32 number);
	//实现类在蓝图中实现接口
	UFUNCTION(BlueprintCallable, BlueprintImplementableEvent, Category = "Trigger Reaction")
		void ReactToTrigger_ImplementableEvent();
ReactToTriggerInterface.cpp
#include "ReactToTriggerInterface.h"
void IReactToTriggerInterface::ReactToTrigger_Virtual()
	// unimplemented(); //该宏将在执行代码行时发出调试语句, 中断
	UE_LOG(LogTemp, Warning, TEXT("ReactToTrigger_Virtual 被调用, From 接口本身"));
MyDrone.h  此类继承自Pawn类，无关本文主题
#include "ReactToTriggerInterface.h"
#include "MyDrone.generated.h"
UCLASS()
class TIPS_API AMyDrone : public ADrone, public IReactToTriggerInterface
	GENERATED_BODY()
public:
	virtual void ReactToTrigger_PureVirtual() override;
	//可蓝图调用，貌似通用写法
	UFUNCTION(BlueprintCallable, BlueprintNativeEvent, Category = "Trigger Reaction")
		void ReactToTrigger_NativeEvent1(int32 number);
		virtual void ReactToTrigger_NativeEvent1_Implementation(int32 number) override;
	//蓝图可调用,,貌似和上面没区别
	virtual bool ReactToTrigger_NativeEvent2_Implementation(int32 number) override;
	//void ReactToTrigger_ImplementableEvent();需要在蓝图实现	
MyDrone.cpp
#include "MyDrone.h"
void AMyDrone::ReactToTrigger_PureVirtual()
	UE_LOG(LogTemp, Warning, TEXT("ReactToTrigger_PureVirtual 被调用, From MyDrone"));
void AMyDrone::ReactToTrigger_NativeEvent1_Implementation(int32 number)
	UE_LOG(LogTemp, Warning, TEXT("ReactToTrigger_NativeEvent1 被调用, From MyDrone"));
bool AMyDrone::ReactToTrigger_NativeEvent2_Implementation(int32 number)
	UE_LOG(LogTemp, Warning, TEXT("ReactToTrigger_NativeEvent2 被调用, From MyDrone"));
	return true;
c++ 调用接口可以先判断该类是否有实现接口
// 如果OriginalObject实现了UReactToTriggerInterface，则bisimplemated将为true。
bool bIsImplemented = OriginalObject->GetClass()->ImplementsInterface(UReactToTriggerInterface::StaticClass()); 
// 如果OriginalObject实现了UReactToTrigger，bIsImplemented将为true。
bIsImplemented = OriginalObject->Implements<UReactToTriggerInterface>(); 
// 如果OriginalObject实现了UReactToTriggerInterface，则ReactingObject将为非空。
IReactToTriggerInterface* ReactingObject = Cast<IReactToTriggerInterface>(OriginalObject); 
原生 虚函数调用按照原生C++调用即可
UFUCNTION()修饰的接口函数则以 I接口名::Execute_函数名( 接口实例, 函数参数) 调用
MyTriggerBox.h
#pragma once
#include "CoreMinimal.h"
#include "Engine/TriggerBox.h"
#include "MyTriggerBox.generated.h"
UCLASS()
class TIPS_API AMyTriggerBox : public ATriggerBox
	GENERATED_BODY()
public:
	virtual void BeginPlay() override;
	UFUNCTION()
	void HandleOverlap(AActor* OverlappedActor, AActor* OtherActor );	
MyTriggerBox.cpp
#include "MyTriggerBox.h"
#include "Components/BoxComponent.h"
#include "ReactToTriggerInterface.h"
void AMyTriggerBox::BeginPlay()
	//放在构造函数好像不起作用
	OnActorBeginOverlap.AddDynamic(this, &AMyTriggerBox::HandleOverlap);
void AMyTriggerBox::HandleOverlap(AActor* OverlappedActor, AActor* OtherActor )
	UClass* ActorClass = OtherActor->GetClass();
	if (ActorClass->ImplementsInterface(UReactToTriggerInterface::StaticClass()))
		UE_LOG(LogTemp, Warning, TEXT("是否实现接口判断方法一"));
		IReactToTriggerInterface* ReactToTriggerInterface1 = CastChecked<IReactToTriggerInterface>(OtherActor);
		ReactToTriggerInterface1->ReactToTrigger_PureVirtual(); 
		ReactToTriggerInterface1->ReactToTrigger_Virtual();
		IReactToTriggerInterface::Execute_ReactToTrigger_NativeEvent1(OtherActor, 16);
		IReactToTriggerInterface::Execute_ReactToTrigger_NativeEvent2(OtherActor, 32);
		IReactToTriggerInterface::Execute_ReactToTrigger_ImplementableEvent(OtherActor);
	if (OtherActor->Implements<UReactToTriggerInterface>())
		UE_LOG(LogTemp, Warning, TEXT("是否实现接口判断方法二"));
		IReactToTriggerInterface::Execute_ReactToTrigger_NativeEvent1(OtherActor, 16);
		IReactToTriggerInterface::Execute_ReactToTrigger_NativeEvent2(OtherActor, 32);
	IReactToTriggerInterface* ReactToTriggerInterface2 = Cast<IReactToTriggerInterface>(OtherActor);
	if (ReactToTriggerInterface2)
		UE_LOG(LogTemp, Warning, TEXT("是否实现接口判断方法三"));
		IReactToTriggerInterface::Execute_ReactToTrigger_ImplementableEvent(OtherActor);
实施蓝图接口