NewObject usage and setup

Development Programming & Scripting
1

Hi Guys,

Got another noob C++ question again… I have the below function: that seems to cause it to crash:

UGrid* AGalaxy::GetGrid(const FVector2D &GetLocation, bool CreateIfMissing)
{
	int N = (GetLocation.X * GalaxySize) + GetLocation.Y;
	UGrid* newGrid = GridLookup[N];
	
	if (!newGrid)
	{
		if (CreateIfMissing == false) return nullptr;
		
		// create an empty Grid data struct if you need one
		GridLookup[N] = NewObject<UGrid>(UGrid::StaticClass());
		newGrid = GridLookup[N];
		//newGrid->SetGridIndex(GetLocation);
	}

	return newGrid;
}

Looking at the debug in VS i get the below which i’m guessing means the UGrid object didn’t create properly but I’m not sure. I can post more code if needed but hopefully it’s an obvious error and this is enough. The VS local look like this when it crashed

77119-capture.png
77119-capture.png1139×162 4.85 KB

Any help would be great, thanks!

2

The problem is here: GridLookup[N] = NewObject(UGrid::StaticClass());

When you use NewObject to create a UObject, the first parameter to be passed should be the Outer.

For example:
GridLookup[N] = NewObject(this);

Note:
If you want to pass a specific child class for this object, then pass the class name as the second parameter.
For example:
You have a BluePrint, which extends the UGrid, called BP_Grid.
In the BP_Grid you change parameters and input values that you want to use in the game.
In order to create objects using the BP_Grid, you have to pass the BP_Grid as class, then create objects using the BPGridClass:
GridLookup[N] = NewObject(this, BPGridClass);

The BPGridClass declaration in the .h file:
UPROPERTY(EditAnywhere, BlueprintReadWrite)
TSubclassOf BPGridClass;