WaveSpawner.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class WaveSpawner : MonoBehaviour 
{
	public enum SpawnState { SPAWNING, WAITING, COUNTING };
	[System.Serializable]
	public class Wave
	{
		public string name;
		public Transform enemy;
		public int count;
		public float rate;
	}

	public Transform[] spawnPoints;

	public Wave[] waves;
	private int nextWave = 0;
	public float timeBetweenWaves = 5f;
	private float waveCountdown;

	private float searchCountdown = 1f;

	private SpawnState state = SpawnState.COUNTING;

	void Start()
	{
		if (spawnPoints.Length == 0)
		{
			Debug.LogError("No spawn points referenced.");
		}

		waveCountdown = timeBetweenWaves;
	}

	void Update()
	{
		if (state == SpawnState.WAITING)
		{
			// Checking if enemies are still alive
			if (!EnemyIsAlive())
			{
				// Begin a new round
				Debug.Log("Wave Completed!");
				return;
			}
			else
			{
				return;
			}
		}

		if (waveCountdown <= 0)
		{
			if (state != SpawnState.SPAWNING)
			{
				StartCoroutine(SpawnWave(waves[nextWave]));
			}
		}
		else
		{
			waveCountdown -= Time.deltaTime;
		}
	}

	void WaveCompleted()
	{
		Debug.Log("Wave Completed!");

		state = SpawnState.COUNTING;
		waveCountdown = timeBetweenWaves;

		if (nextWave + 1 > waves.Length - 1)
		{
			nextWave = 0;
			Debug.Log("ALL WAVES COMPLETED! Looping....");
		}
		else
		{
			nextWave++;
		}
	}

	bool EnemyIsAlive()
	{
		searchCountdown -= Time.deltaTime;

		if (searchCountdown <= 0f)
		{
			searchCountdown = 1f;

			if (GameObject.FindGameObjectWithTag("Enemy") == null)
			{
				return false;
			}
		}
		return true;
	}

	IEnumerator SpawnWave(Wave _wave)
	{
		Debug.Log("" + _wave.name);
		state = SpawnState.SPAWNING;

		for (int i = 0; i < _wave.count; i++)
		{
			SpawnEnemy(_wave.enemy);
			yield return new WaitForSeconds( 1f/_wave.rate );

		}

		// Spawn
		state = SpawnState.WAITING;

		yield break;
	}

	void SpawnEnemy(Transform _enemy)
	{
		Instantiate(_enemy, transform.position, transform.rotation);

		Transform _sp = spawnPoints[Random.Range(0, spawnPoints.Length)];

		Debug.Log("Spawning Enemy: " + _enemy.name);

	}
}