How to add a wave in my spawn script

Okay basically I have a 2D game which I would like to spawn an prefab in cube, I have a spawning script but I would like to make this script into a wave spawning script. Where at a certain time the waves becomes faster then faster and so on. If there is anyway of doing this or an example you can give that would be amazing and i would appreciated it so much! Thank you!
Here is my script:

using UnityEngine;
using System.Collections;

public class Atempt1 : MonoBehaviour {

public GameObject ObjectToSpawn;   
public float RateOfSpawn = 1;
public float SpawnDelay = 20f;
private float nextSpawn = 0;

// Update is called once per frame
void Update () {           
	
	if (Time.time > nextSpawn) {
		nextSpawn = Time.time + RateOfSpawn;
	}
}
	void Start(){
			Invoke("Spawn", SpawnDelay);
		}
		
		void Spawn () {           
			// Random position within this transform
			Vector3 rndPosWithin;
			rndPosWithin = new Vector3(Random.Range(-1f, 1f), Random.Range(-1f, 1f), Random.Range(-1f, 1f));
			rndPosWithin = transform.TransformPoint(rndPosWithin * .5f);
			Instantiate(ObjectToSpawn, rndPosWithin, transform.rotation);  
			
			Invoke("Spawn",SpawnDelay);
		}

}

you can try something like this

WARNING this quickly gets out of hand, so its worth checking the numbers or having some method of seeing if the previous wave was cleared first.

using UnityEngine;
using System.Collections;

public class spawner : MonoBehaviour {

	// Use this for initialization
	public GameObject spawnThing;
	int spawnLevel = 1;
	int spawnCount;
	float spawnDelay = 3f; //seconds between waves
	float minSpawnDelay = 0.1f; // the shortest time between waves possible

	float currentDelay;


	void Start () {
		currentDelay = Time.time + spawnDelay;
	}
	
	// Update is called once per frame

	void Update () {
	if (Time.time > currentDelay) {
			for(int i = 0; i < spawnLevel; i++)
			{
				spawnEnemy();
			}
			spawnLevel ++; //increase the spawn level
			spawnDelay -= spawnLevel/10; //just an approximation, this will take 0.1 seconds off per level
			if(spawnDelay < minSpawnDelay)
			{
				spawnDelay = minSpawnDelay; // this ensures that the spawn delay does not drop below this time.
			}
			currentDelay = Time.time + spawnDelay;
		}
	}

	void spawnEnemy()
	{
		GameObject temp = Instantiate (spawnThing, transform.position, Quaternion.identity) as GameObject;
		//do whatever you want with temp
		Destroy (temp, 2);// this for debug to make sure it doesnt get overrun.
	}
}

hope it helps :slight_smile: