Event not being invoked

Questions & Answers
1

I followed a Unity Events tutorial and adapted it to my game link: Unity How to structure your code with UnityEvents - Tutorial - YouTube
I have 1 script called GameLogicScript, 1 script called UIScript and 1 script for the events called Events

When I invoke an event from the UIScript, the GameLogicScript detects it and does accordingly how it is supposed to do, however, when I try to do it the other way (GameLogicScript invokes and event and UIScript detects it is not working)
This is my relevant code:

--------------- UIScript ---------------

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

public class UIScript : MonoBehaviour
{
    public GameObject pauseMenuUI;
    public GameObject gameOverMenuUI;
    public GameObject mainMenuUI;
    public GameObject gameplayUI;
    //Play - pause button
    public Button pauseResumeButton;
    public Sprite pauseSprite;
    public Sprite playSprite;
    //Score
    public Text scoreText;
    private int score;

    void Start()
    {
        //Listen to events
        Events.gameOver.AddListener(GameOver);
        Events.increaseScore.AddListener(IncreaseScore);
        Events.playAgainUI.AddListener(PlayAgain);
    }

    // Update is called once per frame
    void Update()
    {
        if(Input.GetKeyDown(KeyCode.Escape)){
            ResumeOrPause();
        }
    }

    public void PlayAgain(){
        Debug.Log("Holiwis");
        pauseMenuUI.SetActive(false);
        gameOverMenuUI.SetActive(false);
        mainMenuUI.SetActive(false);
        gameplayUI.SetActive(true);
    }

    public void PlayAgainForButton(){
        Events.playAgainGameLogic.Invoke();
    }
}

--------------- GameLogicScript ---------------

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

public class GameLogicScript : MonoBehaviour
{
    //Cameras
    public GameObject menuCamera;
    public GameObject gameplayCamera;
    //Bool
    public static bool isPlaying = false;
    public static bool playAgain = false;
    //Float
    private float InstantiateToppingY;
    //GameObject
    private GameObject NextTopping;
    public GameObject NewToppingPrefab;
    //Others
    public Sprite[] ToppingSprites;
    
    void Start(){
        
        InstantiateToppingY = -2;
        //Listen to events
        Events.instantiateTopping.AddListener(InstantiateTopping);
        Events.resume.AddListener(Resume);
        Events.pause.AddListener(Pause);
        Events.mainMenu.AddListener(LoadMenu);
        Events.startGame.AddListener(StartGame);
        Events.playAgainGameLogic.AddListener(PlayAgain);
        
        if(playAgain){
            Debug.Log("Invoked event");
            Events.playAgainUI.Invoke();
            StartGame();
            
        }
        else
            Pause();
    }

    public void PlayAgain(){
        playAgain = true;
        SceneManager.LoadScene("Main");
    }
}

--------------- Events ---------------

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

public static class Events
{
    public static UnityEvent gameOver = new UnityEvent();
    public static UnityEvent instantiateTopping = new UnityEvent();
    public static UnityEvent increaseScore = new UnityEvent();
    public static UnityEvent resume = new UnityEvent();
    public static UnityEvent pause = new UnityEvent();
    public static UnityEvent mainMenu = new UnityEvent();
    public static UnityEvent startGame = new UnityEvent();
    public static UnityEvent playAgainGameLogic = new UnityEvent();
    public static UnityEvent playAgainUI = new UnityEvent();

}
2

Hi,
I had a similar problem,
Please change like this and should work.

using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.Events;
 
 public static class Events
 {
     public static UnityEngine.Events.UnityEvent gameOver = new UnityEngine.Events.UnityEvent();
     public static UnityEngine.Events.UnityEvent instantiateTopping = new UnityEngine.Events.UnityEvent();
     public static UnityEngine.Events.UnityEvent increaseScore = new UnityEngine.Events.UnityEvent();
     public static UnityEngine.Events.UnityEvent resume = new UnityEngine.Events.UnityEvent();
     public static UnityEngine.Events.UnityEvent pause = new UnityEngine.Events.UnityEvent();
     public static UnityEngine.Events.UnityEvent mainMenu = new UnityEngine.Events.UnityEvent();
     public static UnityEngine.Events.UnityEvent startGame = new UnityEngine.Events.UnityEvent();
     public static UnityEngine.Events.UnityEvent playAgainGameLogic = new UnityEngine.Events.UnityEvent();
     public static UnityEngine.Events.UnityEvent playAgainUI = new UnityEngine.Events.UnityEvent();
 
 }

Please let me know. You might have to change to this same pattern throughout the app.

Rgds

3

Invoking an UnityEvent in Start() could produce a null reference.

public UnityEvent event;

void Start()
{
   event.Invoke(); // Problem
}

Instead, wait one frame:

void Start()
{
   StartCouroutine(InvokeCoroutine()); 
}

IEnumerator InvokeCoroutine()
{
   yield return null;
   event.Invoke();
}