更多说明： https://docs.unity.cn/cn/current/Manual/MessagingSystem.html
例：假设现在有一辆车(Car)进入停车位(ParkingSpace)，在停车位这个类里已经写好车是否进入的逻辑，然后想把车已进入这个消息告诉车，为了实现松散耦合，可以用以下方法：

IOnTriggerParkingSpaceHandler.cs

using UnityEngine.EventSystems;

public interface IOnTriggerParkingSpaceHandler : IEventSystemHandler {
    
    void OnTriggerParkingSpaceHandler (ParkingSpace parkingSpace);
    
}

Car.cs

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

public class Car : MonoBehaviour, IOnTriggerParkingSpaceHandler {
    
    void IOnTriggerParkingSpaceHandler.OnTriggerParkingSpaceHandler (ParkingSpace parkingSpace) {
        Debug.Log("OnTriggerParkingSpace");
    }

}

ParkingSpace.cs

using System.Collections;
using UnityEngine;
using UnityEngine.EventSystems;

public class ParkingSpace : MonoBehaviour {
    
    private void OnTriggerEnter (Collider other) {
        Car car = other.GetComponent<Car>();
        if (car) {
            ExecuteEvents.Execute<IOnTriggerParkingSpaceHandler>(car.gameObject, null, (x, y) => x.OnTriggerParkingSpaceHandler(this));
        }
    }
    
}