NullReferenceException after instantiating.

Questions & Answers
1

I was hoping someone could tell me why I’m getting a NullReferenceException error with this code. I wrote something similar to this in JS and I’m trying to rework everything into C#. The error is coming from the line
mapTile.name = "Map Tile “+xLocation+”, "+zLocation; I have no clue why, I could do this in JS. If I comment it out, I get the same thing with the next line. How do I properly reference something I’ve just instantiated?

public void BuildMap () {
	
	//BuildMap performs a loop which will create map tiles row by row, column by column, with dimensions xBoundary and yBoundary.
	for(int i = 0; i < xBoundary*zBoundary; i++){
		
		//determines the current tiles location in the grid.
		xLocation = (int)i%xBoundary;
		zLocation = (int)Mathf.Floor(i/xBoundary);
		
		//Creates the map tile at coordinates xLocation, 1, zLocation, with no rotation. This object is now GameObject mapTile.
		mapTile = Instantiate (mapTilePrefab, new Vector3(xLocation, 1, zLocation), Quaternion.identity) as Transform;
		
		//Assigns a name to the map tile for the heirarchy.
		mapTile.name = "Map Tile "+xLocation+", "+zLocation;
		mapTileScript = mapTile.FindChild("Map Tile Collider").GetComponent(typeof(MapTileColliderBehaviour)) as MapTileColliderBehaviour;
		
		//Assigns the tile a room value, and its x and z values.
		mapTileScript.roomValue = 0;
		mapTileScript.xGridValue = xLocation;
		mapTileScript.zGridValue = zLocation;
	}
}
2

What you wanna do is instantiate your GameObject as a GameObject and not as a Transform. Changing line 11 from

mapTile = Instantiate (mapTilePrefab, new Vector3(xLocation, 1, zLocation), Quaternion.identity) as Transform;

to

mapTile = Instantiate (mapTilePrefab, new Vector3(xLocation, 1, zLocation), Quaternion.identity) as GameObject;

Should fix your error message. After you do that, you need to remember to change your “mapTile” variable type to GameObject instead of Transform as well.
Hope it helps! :slight_smile: