SetStaticMesh in constructor versus BeginPlay

Development Programming & Scripting
1

Context:

Consider the following code:

.h

UCLASS()
... AHexMap : public AActor
{
	GENERATED_BODY()

public:	
    UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Mesh")
    UStaticMesh* tileMesh;  // Exposed to editor
	UPROPERTY()
	USceneComponent* root;
	UPROPERTY()
	UInstancedStaticMeshComponent* tile;

    ...
}

.cpp

...AHexMap::AHexMap(const FObjectInitializer& ObjectInitializer) : Super(ObjectInitializer)
{

	root = ObjectInitializer.CreateDefaultSubobject<USceneComponent>(this, TEXT("Root"));
	RootComponent = root;

	tile = CreateDefaultSubobject<UInstancedStaticMeshComponent>(TEXT("Tile"));
    tile->SetupAttachment(RootComponent,TEXT("Tile"));

    // Setting static mesh of component in the constructor
    tile->SetStaticMesh(tileMesh);
}
// Instances of tile are created in BeginPlay()

The above code allows a designer to choose which mesh to use for the tile from the editor. The component instances, however, do not render the mesh when written as above. If I instead place the line

tile->SetStaticMesh(tileMesh);

at the very start of BeginPlay(), the mesh renders as expected.

Question:

Why is this happening?

If I had to guess, I would say this is due to either

  1. The lifecycle of UPROPERTY variables assigned values through the editor. In this case a mesh assigned through the editor may not be available on construction (for whatever its worth, I tried placing the line in OnConstruction and it still did not render).

  2. The lifecycle of components. I think components aren’t registered until after the constructor has been called so maybe the component isn’t at the point in its lifecycle where it can be assigned a mesh (?)

Obviously these are shots in the dark. I am just trying to better understand what’s happening here.

2

That’s how Instanced Static Mesh work. You set the mesh or a reference to it then add all the instances you want.

3

This doesn’t really address what I asked, though it might be because I wasn’t clear enough on my part. I am instancing in the body of BeginPlay() in both of the scenarios I bring up. The question is why assigning a static mesh through the editor and setting that mesh in the constructor doesn’t render the mesh for any of the instances - whereas assigning a static mesh through the editor and setting that mesh in BeginPlay does.

I’ll edit the original post to clarify that I am properly instancing in both cases