OnCollision 為自定義的碰撞函數，名稱可以任意，但參數形式必須滿足以下條件

UFUNCTION()void OnCollision(class AActor* OtherActor, class UPRimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult);然后在 PacManCharacter.cpp 文件中的 SetupPlayerInputComponent 函數中添加綁定函數：
GetCapsuleComponent()->OnComponentBeginOverlap.AddDynamic(this, &PacManCharacter::OnCollision);碰撞函數的實現：
void PacManCharacter::OnCollision(class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult){　　GEngine->AddOnScreenDebugMessage(0, 1.0f, FColor::Red, TEXT("PacMan ! "));}
但是以上是老版本的 UE4 支持的格式，編譯會報參數類型不匹配的錯誤
error C2664: 'void TBaseDynamicMulticastDelegate::__Internal_AddDynamic(UserClass *,void (__cdecl AItem::* )(UPrimitiveComponent *,AActor *,UPrimitiveComponent *,int32,bool,const FHitResult &),FName)': cannot convert argument 2 from 'void (__cdecl AItem::* )(AActor *,UPrimitiveComponent *,int32,bool,const FHitResult &)' to 'void (__cdecl AItem::* )(UPrimitiveComponent *,AActor *,UPrimitiveComponent *,int32,bool,const FHitResult &)'
新版本的 UE4 應該對碰撞函數進行如下聲明和定義：
UFUNCTION()void OnCollision(class UPrimitiveComponent* HitComp, class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult & SweepResult);
void PacManCharacter::OnCollision(class UPrimitiveComponent* HitComp, class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult){　　GEngine->AddOnScreenDebugMessage(0, 1.0f, FColor::Red, TEXT("PacMan ! "));}
即增加了第一個參數  class UPrimitiveComponent* HitComp