Trouble with upgrading towers

Questions & Answers
1

I am currently working on a basic TD game, and I’m having a little trouble dealing with upgrades. As of now, I have a bunch of preset-tiles placed on my map, and if you click those towers, it will spawn a tower on top of that tile if the provided conditions are met (if you have enough $ and there isn’t already another tower there).

However, when it comes to upgrading, I’m running into problems. Ideally, what happens is that if I have enough money and I click on the tower/tile, the upgraded tower will replace the current tower. The issue is that I’m unable to get rid of the pre-existing tower.

void OnMouseUpAsButton() {
		GameObject tower;
		if (!has_tower) {
			if (spawn.GetKash() < cost) {
				GetComponent<AudioSource> ().Play ();
			}
			else {
				tower = Instantiate (tower_prefab);
				tower.transform.position = transform.position + Vector3.up;
				spawn.MakeKash (-cost);
				has_tower = true;
			}
		} else {
			if (!upgraded) {
				if (spawn.GetKash() < upgrade_cost) {
					GetComponent<AudioSource> ().Play ();
				}
				else {
					//Destroy(tower);
					GameObject upgrade = (GameObject)Instantiate (upgrade_prefab);
					upgrade.transform.position = transform.position + Vector3.up;
					spawn.MakeKash (-upgrade_cost);
					upgraded = true;
				}
			}
		}
	}

If I don’t initialize tower, then I get an error as it may be unassigned in the Else statement. However, if I do initialize tower, what happens is that clicking only results in spawning a bunch of towers without destroying any single one of them.

Any help would be greatly appreciated!

2

Ok i’m sure to uderstand what’s your problem but for me there is a fondamental problem.

You must keep you variable tower. The problem is that you declare it in a function, so when the function finish the variable tower is destroy. You loose your link to the tower.

Put GameObject tower at the top of your class and you can uncomment //Destroy(tower);
Then when you upgrade your tower GameObject tower = (GameObject)Instantiate (upgrade_prefab);

I change upgrade by tower because if you want to upgrade one more time, it will works again if you change the upgrade_prefab.