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C# Coroutine doesnt works in Unity

Im trying to make a basic platformer game and my level controller script isnt working, it needs to load loading scene first and then nextlevel but it constantly loads the nextlevel
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
public class LevelController : MonoBehaviour
{
[SerializeField] string nextLevel;
private Gem[] gems;
void OnEnable()
{
gems = FindObjectsOfType<Gem>();
}
IEnumerator Wait()
{
yield return new WaitForSeconds(3);
}
void Update()
{
if (ReadyToNextLevel())
{
SceneManager.LoadScene("Loading");
StartCoroutine(Wait());
SceneManager.LoadScene(nextLevel);
}
}
bool ReadyToNextLevel()
{
foreach (var gem in gems)
{
if (gem.gameObject.activeSelf)
{
return false;
}
}
return true;
}
}

There are two big issues in your code.
Starting a Coroutine does not delay the method that started the routine!
If you want something happening after the Coroutine is finished you need to either move it into the routine itself or use a callback.
However, the thing is: You are loading a new scene, namely the "Loading" scene -> The current scene is unloaded -> the object this script is on gets destroyed -> the routine would no further executed.
Except your object is DontDestroyOnLoad which seems not the case from your code.
So in order to solve both you will need to make sure this object is not destroyed when another scene is loaded, at least not until it finished the loading process.
You could do this like e.g.
public class LevelController : MonoBehaviour
{
[SerializeField] string nextLevel;
private Gem[] gems;
void OnEnable()
{
gems = FindObjectsOfType<Gem>();
// Makes sure this is not destroyed when another scene is load
DontDestroyOnLoad(gameObject);
}
bool alreadyLoading;
IEnumerator Wait(Action whenDone)
{
yield return new WaitForSeconds(3);
// invoke the callback action
whenDone?.Invoke();
}
void Update()
{
if (ReadyToNextLevel() && ! alreadyLoading)
{
alreadyLoading = true;
SceneManager.LoadScene("Loading");
StartCoroutine(Wait(() =>
{
// This will be done after the routine finished
SceneManager.LoadScene(nextLevel);
// Now we don't need this object anymore
Destroy(gameObject);
}));
}
}
bool ReadyToNextLevel()
{
foreach (var gem in gems)
{
if (gem.gameObject.activeSelf)
{
return false;
}
}
return true;
}
}

EDIT: see derHugo's answer. They are more familiar with Unity than I am and point out that your script will be unloaded on scene change.
Your Wait() coroutine yields immediately, so StartCoroutine(Wait()) will return immediately and load the next scene.
If you want to wait three seconds before loading, then put the load inside the coroutine.
Like this:
private bool isLoading;
void Update()
{
if (!isLoading && ReadyToNextLevel())
StartCoroutine(LoadNextLevel());
}
IEnumerator LoadNextLevel()
{
isLoading = true;
SceneManager.LoadScene("Loading");
yield return new WaitForSeconds(3);
SceneManager.LoadScene(nextLevel);
isLoading = false;
}
See Coroutine help for more details

there are two reasons why this doesn't work, firstly when you load into the loading scene the gameObject is destroyed because you haven't told it to DontDestroyOnLoad, so the script will be sort of 'deleted' from the current scene. Second of all, when you call the coroutine, it calls the coroutine and then immediately continuous on to the next line of code, it doesn't wait for the coroutine to finish before moving on. I think derHugo covered how to fix these.

is there a way to delay an if statement/method in c#

So I have a problem with delaying a method from happening in a if statement, this if statement is in another method called OnCollisionExit(). The purpose of this mess is to try to prolong another method in another if statement in another method called OnCollisionStay().
I've made a timer, which actually works. The problem (I think) is that OnCollisionExit() runs through its code only one time... therefore the timer doesn't work (it doesn't reach zero). If you don't undrestand you will do when you read the code
timer method (it is run in the Update() method)
private void Counter()
{
if (counterEnabled)
{
remainingTime = remainingTime - 1 * Time.deltaTime;
}
if (remainingTime <= 0)
{
remainingTime = defaultTime;
counterEnabled = false;
}
}
this is the OnCollisionExit() method
void OnCollisionExit(Collision collision)
{
counterEnabled = true;
if (collision.gameObject == thing && counterEnabled == false)
{
//this is what am trying to delay
DontDoSomething();
}
}
this is the OnCollisionStay() method
void OnCollisionStay(Collision collision)
{
if (collision.gameObject == thing)
{
//this is what Iam trying to prolong
DoSomething();
}
}
if you don't know how the timer works... it works like this:
when OnCollisionExit() runs, it will make a bool (counterEnabled) true
when this happens, a variable(remainingTime) of value 2f will get subtracted by 1 every second
when remainingTime reaches zero or anything less, remainingTime will be equal to defaultTime which is simply a variable holding remainingTime original value (2f), and will turn counterEnabled false.
when counterEnabled turns false, it will allow the if statement in OnCollisionExit() to be true

You could use a coroutine instead :
void OnCollisionExit(Collision collision)
{
StartCoroutine (Countdown());
}
IEnumerator Countdown()
{
yield return new WaitForSeconds (2f);
DontDoSomething ();
}

StartCoroutine is being called so many times (C# Unity)

I'm creating a Pop up menu Option in Unity. Now my Problem here is that the coroutine i made in void update is being called so many times. What i mean by that is on my Unity Console the Debug.Logs are incrementing . It should not right because its already coroutine. Could some help me understand more coroutine and help me solve my little problem .
Here is my code:
[SerializeField]
GameObject Option;
[SerializeField]
Button btn,btn2;
[SerializeField]
GameObject open, close;
[SerializeField]
GameObject[] opt;
bool startFinding = false;
void Start()
{
Option.SetActive(false);
Button popUp = btn.GetComponent<Button>();
Button popUp2 = btn2.GetComponent<Button>();
popUp.onClick.AddListener(PopUpOption);
popUp2.onClick.AddListener(ClosePopUp);
}
void Update()
{
if (startFinding)
{
StartCoroutine(GameOptions());
}
}
IEnumerator GameOptions()
{
//Get All the tags
opt = GameObject.FindGameObjectsWithTag("MobileOptions");
if (opt[0].GetComponent<Toggle>().isOn == true && opt[1].GetComponent<Toggle>().isOn == true)
{
Debug.Log("Disable first the check box then choose only 1 option between" + "'rendering'"+ "and" + "'livestreaming'");
}
//Livestreaming
if (opt[0].GetComponent<Toggle>().isOn == true)
{
Debug.Log("Livestreaming Activate");
} else
{
Debug.Log("Livestreaming Deactivate");
}
//Rendering
if (opt[1].GetComponent<Toggle>().isOn == true)
{
Debug.Log("Rendering Activate");
} else
{
Debug.Log("Rendering Deactivate");
}
//Fog
if (opt[2].GetComponent<Toggle>().isOn == true)
{
Debug.Log("Fog Activated");
} else
{
Debug.Log("Fog Deactivated");
}
//Camera Effect
if (opt[3].GetComponent<Toggle>().isOn == true)
{
Debug.Log("Camera Effect Activated");
} else {
Debug.Log("Camera Effect Deactivated");
}
yield return null;
}
void PopUpOption()
{
startFinding = true;
//Disable The Mobile Option Button
open.SetActive(false);
//Enable the Close Option Button
close.SetActive(true);
//activate the Mobile Options
Option.SetActive(true);
}
void ClosePopUp()
{
startFinding = false;
//eanble the mobile option button
open.SetActive(true);
//disable the close option button
close.SetActive(false);
//deactivate the Mobile Option
Option.SetActive(false);
}

Here is how coroutines work:
Let's say I have a couroutine function called MyRoutine (in your case, you called it GameOptions)
private IEnumerator MyRoutine()
Then, anywhere in my code, calling
StartCoroutine(MyRoutine));
Is going to simply call MyRoutine like any usual method. So if you call it in update, it will be called all the time, as any method would. This is not what you want. What make coroutines special is that you can use the yield keyword in them. There are many ways to use it but the most used (and simple) one is to do yield return null
yield return null means "Stop this coroutine, but resume the execution on next frame". You don't need to call any other function (certainly not StartCoroutine). The execution will resume next frame.
To go back to what you posted in your question, you wrote yield return null at the end. So your method is executing, and just at the end, stops and resumes next frame, but since there is nothing left to do, it exits on the next frame.
A typical way to use coroutines is to have the yield return null in a while loop, so when it resumes, it continues the loop. Here is an example that do it
private IEnumerator MyRoutine()
{
while(running) //running is a member bool that you could set to false to exit
{
// Do all the stuff you want to do in ONE frame
// ...
yield return null;
}
}
Typically, the StartCoroutine would be called in the Start() function, or later when an event is triggered.
If you want to know more about coroutine, or check that you understood them properly, check out this page: https://docs.unity3d.com/Manual/Coroutines.html
or this video https://unity3d.com/learn/tutorials/topics/scripting/coroutines
// Edit: quickly present one useful option
In the snippet above, the while loop is very similar to the Update function (the inside of the loop is executed each frame). One nice option is to replace
yield return null
by
yield return new WaitForSeconds(waitTime)
where waitTime is a the time you want to wait before resuming, in seconds
// End of edit

Do not use StartCoroutine() in the Update method. Call it in another method and use a while loop inside your coroutine function if needed. Just control your StartCoroutine() outside of Update method

Update is called every frame, if your condition is ever true, you launch your coroutine every frame.
Just set down your flag to only join 1 time.
void Update()
{
if (startFinding)
{
startFinding = false;
StartCoroutine(GameOptions());
}
}

Sprite not changing when key is pressed - unity 2D

Currently I'm simply trying to change the sprites candle from unlit to lit when the player has 'picked up' both the candle and the matches and the candle will 'go out' after a certain amount of time. However, when the space bar is pressed the transition from unlit to lit isn't occurring, even though the debug log is returning true when it should. I'm posting here to get some guidance as I have spent most of the day looking online and literally have no idea how to proceed.
Basically the images I am trying to transition between are two different images which are in the sprites folder under assets.
This is what I've got so far.
//the two sprites transition
public Sprite unlitCandle;
public Sprite litCandle;
private SpriteRenderer spriteRenderer;
bool pickUpMatches = false;
bool pickUpCandle = false;
float timeRemaining =5;
bool candleLit = false;
// Use this for initialization
void Start () {
spriteRenderer = GetComponent<SpriteRenderer>();
if (spriteRenderer.sprite == null)
spriteRenderer.sprite = unlitCandle;
}
// Update is called once per frame
private void OnTriggerEnter2D(Collider2D collision)
{
if(collision.gameObject.CompareTag("Matches"))
{
collision.gameObject.SetActive(false);
pickUpMatches = true;
}
if (collision.gameObject.CompareTag("UnlitCandle"))
{
collision.gameObject.SetActive(true);
pickUpCandle = true;
}
}
public void CandleTimer()
{
if (candleLit == true)
{
timeRemaining = 5;
timeRemaining -= Time.deltaTime;
if (timeRemaining <= 0)
{
candleLit = false;
spriteRenderer.sprite = unlitCandle;
}
}
}
public void ChangeSprite()
{
if (spriteRenderer.sprite == unlitCandle)
{
spriteRenderer.sprite = litCandle;
}
}
void Update () {
if (pickUpCandle == true && pickUpMatches == true)
{
//Debug.Log(candleLit);
if (Input.GetKey(KeyCode.Space) && !candleLit)
{
CandleTimer();
ChangeSprite();
Debug.Log(timeRemaining);
candleLit = true;
//Debug.Log(candleLit);
}
}
}
}

Try comparing with a method like equals() instead of == in
spriteRenderer.sprite == unlitCandle
Because right now you are just comparing references and not the objects.
At least I think thats the problem.

There are a few possible issues with your code. First, you are calling changeSprite at the top of Update, which means that it is unconditionally being called every frame. Therefore, after a single frame of your candle being unlit, it will immediately change its sprite to litCandle.
I assume that the reason you are calling changeSprite every frame is in order to process the timer if you have a lit candle already. Really, you should move the code to process the timer (your whole second if statement in changeSprite) to a separate function and name it something like processCandleTimer. Call that at the top of Update and save the changeSprite method to only be called on the keypress.
Lastly, the issue that I suspect is giving you the most trouble is that you aren't resetting your timer, timeRemaining. The first time you light the candle the timer will go down to 0 after the 5 seconds pass. Every time changeSprite is run after that, you will change the sprite to litCandle in the first if statement and then immediately change it back to unlitCandle because the timer is 0 in the second. To remedy this, you need to add a line like timeRemaining = 5.0f; when the key is hit.

Delay within an if in C#

How can I create a delay after the fade in, so that the text stays on screen for a few seconds? I used an IEnumerator and a coroutine, but it does nothing. I also tried placing it right after the first else.
What happens at the moment is the text fades out before having the chance to fade in. The text appears momentarily in semi-clear and disappears. It's for a Unity project.
Also, Thread.Sleep won't do.
Here's the piece of code in question:
IEnumerator Pause ()
{
yield return new WaitForSecondsRealtime(5);
}
void OnTriggerStay2D(Collider2D interCollider)
{
if (Input.GetKeyDown(KeyCode.E))
{
displayInfo = true;
}
else
{
displayInfo = false;
}
}
void FadeText()
{
if (displayInfo == true)
{
text1.text = string1;
text1.color = Color.Lerp(text1.color, Color.white, fadeTime * Time.deltaTime);
}
else
{
StartCoroutine(Pause());
text1.color = Color.Lerp(text1.color, Color.clear, fadeTime * Time.deltaTime);
}
}

Your code should read:
void Update()
{
if (fadingOut)
{
// fade out with lerp here
}
}
IEnumerator Pause()
{
yield return new WaitForSecondsRealtime(5);
fadingOut = true;
}
void FadeText()
{
if (displayInfo == true)
{
text1.text = string1;
text1.color = Color.Lerp(text1.color, Color.white, fadeTime * Time.deltaTime);
}
else
{
StartCoroutine(Pause());
}
}
You have the right idea of using a coroutine, but didn't quite get the execution right. When you invoke a method on coroutine, it will be executed in parallel with the main thread. In your code, the Pause() method is running alongside the Color.Lerp. If you want the fading to wait until after the pause is complete, they must be on the same coroutine.
Edit:
As pointed out, this won't work if you're calling FadeText() on each frame. But this shows you how you can easily set a flag and wait until the pause time is complete before fading.

You just need to add the text fade to the coroutine.
IEnumerator Pause()
{
yield return new WaitForSecondsRealtime(5);
text1.color = Color.Lerp(text1.color, Color.clear, fadeTime * Time.deltaTime);
}
And just start the coroutine in your else statement. This way it will execute the wait for seconds, and then the fade whenever you call it.

Most easy way is to use LeanTween asset. It's free and have a lot of other usefull features that I use in EVERY project.
It's really awesome lib.
LeanTween.DelayedCall(1f,()=>{ /*any code that will be called after 1 second will pass*/ });
or
LeanTween.DelayedCall(1f, SomeMethodWithoutParams());