Scene transitions in Unity - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output when loading a scene asynchronously?

Consider this Unity C# code snippet that loads a scene asynchronously. What will be printed to the console?

Unity

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

public class SceneLoader : MonoBehaviour
{
    IEnumerator Start()
    {
        AsyncOperation asyncLoad = SceneManager.LoadSceneAsync("Level2");
        while (!asyncLoad.isDone)
        {
            Debug.Log($"Loading progress: {asyncLoad.progress * 100}%");
            yield return null;
        }
        Debug.Log("Scene loaded!");
    }
}

A

Loading progress: 0%
Loading progress: 90%
Loading progress: 90%
Scene loaded!

B

Loading progress: 0%
Loading progress: 0%
Loading progress: 0%
Scene loaded!

C

Loading progress: 0%
Loading progress: 50%
Loading progress: 100%
Scene loaded!

D

Loading progress: 0%
Loading progress: 0.9%
Loading progress: 0.9%
Scene loaded!

💡 Hint

Remember that asyncLoad.progress goes from 0 to 0.9 before completion.

In Unity, AsyncOperation.progress ranges from 0 to 0.9 while loading. It reaches 0.9 when loading is almost done, then isDone becomes true. So the progress logs show values up to 90%.

🧠 Conceptual

intermediate

Which method correctly unloads a scene in Unity?

You want to unload a scene named "Menu" to free memory. Which method call is correct?

A SceneManager.DeleteScene("Menu");

B SceneManager.LoadScene("Menu", LoadSceneMode.Unload);

C SceneManager.UnloadSceneAsync("Menu");

D SceneManager.RemoveScene("Menu");

💡 Hint

Look for the official method to unload scenes asynchronously.

Unity provides SceneManager.UnloadSceneAsync to unload scenes. Other methods like RemoveScene or DeleteScene do not exist.

🔧 Debug

advanced

Why does this scene transition cause a freeze?

This code causes the game to freeze when transitioning scenes. What is the main reason?

Unity

using UnityEngine;
using UnityEngine.SceneManagement;

public class FreezeOnLoad : MonoBehaviour
{
    void Start()
    {
        SceneManager.LoadScene("GameScene");
        Debug.Log("Scene loaded");
    }
}

A The Debug.Log statement causes an infinite loop.

B LoadScene is called synchronously on the main thread, blocking until the scene loads.

C The scene name "GameScene" is misspelled causing an error.

D Start method cannot call SceneManager.LoadScene.

💡 Hint

Think about how LoadScene works and its effect on the main thread.

SceneManager.LoadScene loads the scene synchronously by default, blocking the main thread and causing the freeze until loading finishes.

📝 Syntax

advanced

Which code snippet correctly implements a fade transition before loading a scene?

You want to fade out the screen before loading a new scene. Which code snippet is syntactically correct and will work?

A

IEnumerator FadeAndLoad() {
    yield return FadeOut();
    SceneManager.LoadSceneAsync("NextScene");
}

B

void FadeAndLoad() {
    StartCoroutine(FadeOut());
    SceneManager.LoadScene("NextScene");
}

C

IEnumerator FadeAndLoad() {
    StartCoroutine(FadeOut());
    yield return SceneManager.LoadSceneAsync("NextScene");
}

D

IEnumerator FadeAndLoad() {
    yield return StartCoroutine(FadeOut());
    SceneManager.LoadScene("NextScene");
}

💡 Hint

Remember that to wait for a coroutine, you must yield return it.

Option D correctly yields the FadeOut coroutine before loading the scene synchronously. Option D does not wait for fade to finish. Option D incorrectly yields LoadSceneAsync without starting it as a coroutine. Option D does not yield LoadSceneAsync and does not start it as coroutine.

🚀 Application

expert

How to keep an object alive across scene transitions?

You want a music player object to continue playing music without restarting when changing scenes. Which code snippet achieves this?

A

void Awake() {
    DontDestroyOnLoad(gameObject);
}

B

void Start() {
    SceneManager.LoadScene("NextScene");
}

C

void Awake() {
    Destroy(gameObject);
}

D

void OnEnable() {
    SceneManager.UnloadSceneAsync("CurrentScene");
}

💡 Hint

Look for the Unity method that prevents destruction on scene load.

DontDestroyOnLoad marks the object to persist across scene loads. Other options either destroy the object or do unrelated scene loading/unloading.