Spawn Blueprints with C++ code

Development Programming & Scripting Blueprint
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I’ve read a lot of posts about this and I still can’t get it working, I’m completely lost.
I want to spawn a bullet hole decal.

please read this post
I don’t get it. Where can I select the blueprint in the editor?

My current code (crashes):

projectile.h

UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = BPClasses)
UClass* bulletHoleBP;

projectile.cpp

world->SpawnActor(bulletHoleBP);

Also everytime I turn on the editor it shows:

Error: CDO Constructor: Failed to find /Game/Blueprints/bullethole.bullethole_C

2

Do you do anything in constructors?

3

Have you see this tutorial? Unreal Engine 4 C++ Tutorial Version 4.0.2: Charged Projectile - YouTube

here is my enemy bullet class:

.H

UCLASS()
class TSTEST_API AEnemyWeapon1 : public APawn
{
	GENERATED_UCLASS_BODY()

		/** Sphere collision component */
		UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = Projectile)
	class UStaticMeshComponent* ProjectileMesh;

	/** Projectile movement component */
	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = Movement)
	class UProjectileMovementComponent* ProjectileMovement;

	/** Function to handle the projectile hitting something */
	UFUNCTION()
		void OnHit(AActor* OtherActor, UPrimitiveComponent* OtherComp, FVector NormalImpulse, const FHitResult& Hit);
	
	
	
	
};

this is my .CPP

  #include "GameFramework/ProjectileMovementComponent.h"  //You must include this to work.
    
    AEnemyWeapon1::AEnemyWeapon1(const class FObjectInitializer& PCIP)
    	: Super(PCIP)
    {
    	// Static reference to the mesh to use for the projectile
    	static ConstructorHelpers::FObjectFinder<UStaticMesh> ProjectileMeshAsset(TEXT("'/Game/Meshes/objects/SM_Projectile.SM_Projectile'"));
    
    	// Create mesh component for the projectile sphere
    	ProjectileMesh = PCIP.CreateDefaultSubobject<UStaticMeshComponent>(this, TEXT("ProjectileMesh0"));
    	ProjectileMesh->SetStaticMesh(ProjectileMeshAsset.Object);
    	ProjectileMesh->AttachTo(RootComponent);
    	ProjectileMesh->BodyInstance.SetCollisionProfileName("Projectile");			// Collision profiles are defined in DefaultEngine.ini
    	ProjectileMesh->OnComponentHit.AddDynamic(this, &AEnemyWeapon1::OnHit);	      //.AddDynamic(this, &ATStestProjectile::OnHit);		// set up a notification for when this component hits something
    	RootComponent = ProjectileMesh;
    
    	// Use a ProjectileMovementComponent to govern this projectile's movement
    	ProjectileMovement = PCIP.CreateDefaultSubobject<UProjectileMovementComponent>(this, TEXT("ProjectileMovement0"));
    	ProjectileMovement->UpdatedComponent = ProjectileMesh;
    	ProjectileMovement->InitialSpeed = 500.f;
    	ProjectileMovement->MaxSpeed = 1000.f;
    	ProjectileMovement->bRotationFollowsVelocity = true;
    	ProjectileMovement->bShouldBounce = false;
    	ProjectileMovement->ProjectileGravityScale = 0.f; // No gravity
    
    	// Die after 3 seconds by default
    	InitialLifeSpan = 3.0f;
    }



void AEnemyWeapon1::OnHit(AActor* OtherActor, UPrimitiveComponent* OtherComp, FVector NormalImpulse, const FHitResult& Hit)
{

	// Only add impulse and destroy projectile if we hit a physics
	if ((OtherActor != NULL) && (OtherActor != this) && (OtherComp != NULL) && OtherComp->IsSimulatingPhysics())
	{
		OtherComp->AddImpulseAtLocation(GetVelocity() * 20.0f, GetActorLocation());
	}
	Destroy();
}

this is my enemy that i’m attaching the bullet blueprint to:

#include "ParticleDefinitions.h"
#include "EnemyWeapon1.h"  //must include bullet header file to work
#include "Engine.h" // get world functions

......


//in enemy header file i add:   

void Fire();

	/* How fast the weapon will fire */
	UPROPERTY(Category = Gameplay, EditAnywhere, BlueprintReadWrite)
		float FireRate;

	/* Handler for the fire timer expiry */
	void ShotTimerExpired();

	bool bFire;

enemy CPP :

void AZplane::Fire()
{

	if (bFire == true)
	{

		const FRotator FirRot = PlaneComponent->GetSocketRotation("gunsock");
		// Spawn projectile at an offset from this pawn
		const FVector SpawnLocation = PlaneComponent->GetSocketLocation("gunsock"); // +FireRotation.RotateVector(GunOffset); //GetActorLocation()


		UWorld* const World = ();
		//if (World != NULL)
		//{
		// spawn the projectile
		World->SpawnActor<AEnemyWeapon1>(SpawnLocation, FirRot);


		()->GetTimerManager().SetTimer(this, &AZplane::ShotTimerExpired, FireRate);

		bFire = false;

	}
}

void AZplane::ShotTimerExpired()
{
	bFire = true;

}

Build it and load up your editor

After that, I create a Blueprint with your bullet class (search for your class under “all classes”
and then selet it to connect the C++ to your blueprint