Softly killing particle systems

EffectTTL.cs

using Client.Game.Utils;
using System;
using UnityEngine;

namespace Client.Game.Abilities.Utils
{
	public class EffectTTL : MonoBehaviour
	{
		public EffectTTL ()
		{
		}
        

		public float TimeToLive = 0;
		public Action OnExpired;
		
		void Update() {
			TimeToLive -= Time.deltaTime;

			if(TimeToLive <= 0) {
				GameObject.Destroy(this.gameObject);
				if(OnExpired != null) 
					OnExpired();
			}
		}

		public static void Apply(GameObject go, float ttl) {
			go.AddComponent<EffectTTL>().TimeToLive = ttl;
		}
    
        public static void SoftKillParticles(GameObject go, float ttl = 3f) {
            foreach( var ps in go.GetComponentsInChildren<ParticleSystem>()) {
                var pos = ps.transform.position;
                ps.transform.SetParent(null, true);
                ps.transform.position = pos;
                ps.Stop();
                if(ps.GetComponent<EffectTTL>() == null) {
                    Apply(ps.gameObject, ttl);
                }
            }
        }    
    }

    public class AudioFadeTTL : MonoBehaviour
    {
        public AudioFadeTTL()
        {
        }


        public float TimeToLive;
        public float LifeTime;
        public float StartingVolume;

        public AudioSource Source;

        public float NormalizedTime()
        {
            return Mathf.Clamp01(TimeToLive / LifeTime);
        }

        void Update()
        {
            TimeToLive -= Time.unscaledDeltaTime;
            Source.volume = NormalizedTime() * StartingVolume;

            if (TimeToLive <= 0)
            {
                GameObject.Destroy(this.gameObject);
            }
                
        }

        

        public static void Apply(AudioSource src, float ttl)
        {
            var comp = src.gameObject.AddComponent<AudioFadeTTL>();
            comp.Source = src;
            comp.StartingVolume = src.volume;
            comp.TimeToLive = comp.LifeTime = ttl;
        }
        
    }
    
}

This exists so that game objects that have particle systems can be destroyed and their particles can be briefly re-parented to a temporary game object so they can be allowed to play out.

Usage would be something like:
EffectTTL.SoftKillParticles(projectile);