ProjectDDD/Assets/_DDD/_Scripts/GameFramework/Scene/FadeSceneTransitionHandlerSo.cs

using System.Threading.Tasks;
using UnityEngine;

namespace DDD
{
    [CreateAssetMenu(fileName = "FadeSceneTransitionHandlerSo", menuName = "GameFramework/FadeSceneTransitionHandlerSo")]
    public class FadeSceneTransitionHandlerSo : SceneTransitionHandler
    {
        [SerializeField]
        private float _delayBeforeFadeIn = 1f;
        
        [SerializeField]
        private float _fadeOutDuration = 1f;
        
        [SerializeField]
        private float _fadeInDuration = 0.5f;
        
        public override async Task OnBeforeSceneActivate(SceneType sceneType)
        {
            var evt = new FadeOutEvent(_fadeOutDuration);
            EventBus.Broadcast(evt);
            await evt.WaitAsync();
        }

        public override async Task OnAfterSceneActivate(SceneType sceneType)
        {
            float seconds = _delayBeforeFadeIn * 1000;
            await Task.Delay((int)(seconds));
            
            var evt = new FadeInEvent(_fadeInDuration);
            EventBus.Broadcast(evt);
            await evt.WaitAsync();
        }
    }
}