Unity3D Dynamic Quality Settings based on FPS. Runtime reduction of quality based on device performance

QualityManager.cs

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

public class QualityManager : Singleton<QualityManager> {

	private int QUALITY_INDEX = 0;
	public int MIN_FPS = 28;
	public Text qualityUIText;
	private int waitTime = 3;
	void Start(){
		//Application.targetFrameRate = 60;
		QUALITY_INDEX = PlayerPrefs.GetInt("QualityIndex",-1);
		if(QUALITY_INDEX == -1){
			QUALITY_INDEX = QualitySettings.GetQualityLevel();
			Debug.Log("Current Quality Index:" + QUALITY_INDEX);
			Invoke("CheckFrameRate",waitTime);
			qualityUIText.text = QUALITY_INDEX.ToString();
		}
		else{
			UpdateSettings();
			qualityUIText.text = QUALITY_INDEX.ToString();
		}
	}

	void CheckFrameRate(){
		if(FPSCounter.Instance.FPS < MIN_FPS){
			//Drop Qiality Indez
			QUALITY_INDEX--;
			if(QUALITY_INDEX >=0){
				UpdateSettings();
				Invoke("CheckFrameRate",waitTime);
				Debug.Log("Quality Index Decreased to :" + QUALITY_INDEX);
				qualityUIText.text = QUALITY_INDEX.ToString();
			}
			else{
				PlayerPrefs.SetInt("QualityIndex",QUALITY_INDEX);
				AnalyticsManager.Instance.DeviceQuality(QUALITY_INDEX);
			}
		}
		else {
			//Optimal Settings
			PlayerPrefs.SetInt("QualityIndex",QUALITY_INDEX);
			Debug.Log("Saved Quality Index:" + QUALITY_INDEX);
			AnalyticsManager.Instance.DeviceQuality(QUALITY_INDEX);
		}
	}

	void UpdateSettings(){
		QualitySettings.SetQualityLevel(QUALITY_INDEX);
		switch(QUALITY_INDEX){
			case 5:
				break;
			case 4:
				QualitySettings.antiAliasing = 6;
				break;
			case 3:
				QualitySettings.shadowResolution = ShadowResolution.High;
				QualitySettings.antiAliasing = 4;
				break;
			case 2:
				QualitySettings.shadowResolution = ShadowResolution.Medium;
				QualitySettings.antiAliasing = 4;
				HideShadows();
				break;
			case 1:
				QualitySettings.shadowResolution = ShadowResolution.Low;
				QualitySettings.antiAliasing = 2;
				HideShadows();
				break;
			case 0:
				QualitySettings.shadowResolution = ShadowResolution.Low;
				QualitySettings.antiAliasing = 0;
				HideShadows();
				break;
		}
	}

	public void ReduceQuality(){
		QUALITY_INDEX--;
		qualityUIText.text = QUALITY_INDEX.ToString();
		UpdateSettings();
	}

	private void HideShadows(){
		var lights = FindObjectsOfType<Light>() as Light[];
		foreach(Light l in lights){
			l.shadows = LightShadows.None;
		}
	}
}