Scene loading and unloading in Unity - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this scene loading code?

Consider the following Unity C# code snippet that loads a scene asynchronously. What will be printed in the console when the scene finishes loading?

Unity

using UnityEngine;
using UnityEngine.SceneManagement;

public class SceneLoader : MonoBehaviour
{
    void Start()
    {
        StartCoroutine(LoadYourAsyncScene());
    }

    System.Collections.IEnumerator LoadYourAsyncScene()
    {
        AsyncOperation asyncLoad = SceneManager.LoadSceneAsync("Level2");

        while (!asyncLoad.isDone)
        {
            yield return null;
        }

        Debug.Log("Scene Loaded");
    }
}

A Scene Loaded

B No output

C Error: Scene not found

D Scene Loading

💡 Hint

Look at when Debug.Log is called in relation to the async loading completion.

The Debug.Log("Scene Loaded") is called after the asyncLoad.isDone becomes true, meaning the scene finished loading.

🧠 Conceptual

intermediate

Which method unloads a scene in Unity?

You want to remove a scene from memory in Unity during runtime. Which method should you use?

A SceneManager.UnloadSceneAsync("SceneName")

B SceneManager.LoadScene("SceneName")

C SceneManager.ReloadScene("SceneName")

D SceneManager.AddScene("SceneName")

💡 Hint

Think about the method that removes a scene asynchronously.

SceneManager.UnloadSceneAsync unloads the specified scene asynchronously, freeing memory.

🔧 Debug

advanced

Why does this scene not unload properly?

This code tries to unload a scene but the scene remains loaded. What is the likely cause?

Unity

using UnityEngine.SceneManagement;

void UnloadScene()
{
    SceneManager.UnloadSceneAsync("GameScene");
}

A The scene name is case sensitive and "GameScene" is incorrect

B UnloadSceneAsync requires a callback to complete unloading

C UnloadSceneAsync only works in editor mode

D The scene is set as the active scene and cannot be unloaded

💡 Hint

Check if the active scene can be unloaded.

Unity does not allow unloading the active scene. You must set another scene active before unloading.

📝 Syntax

advanced

Which code correctly loads a scene additively?

You want to load a scene without unloading the current one. Which code snippet is correct?

A SceneManager.LoadSceneAsync("Level3", LoadSceneMode.Single);

B SceneManager.LoadScene("Level3", LoadSceneMode.Additive);

C SceneManager.LoadSceneAdditive("Level3");

D SceneManager.LoadScene("Level3", LoadMode.Additive);

💡 Hint

Check the correct enum name for additive loading.

LoadSceneMode.Additive is the correct enum to load a scene additively.

🚀 Application

expert

How to ensure a scene is fully unloaded before loading another?

You want to unload "SceneA" and then load "SceneB" only after unloading completes. Which approach ensures this order?

Unity

using UnityEngine;
using UnityEngine.SceneManagement;

public class SceneSwitcher : MonoBehaviour
{
    public void SwitchScenes()
    {
        // Fill in the blanks
    }
}

A

SceneManager.LoadScene("SceneB");
SceneManager.UnloadSceneAsync("SceneA");

B

SceneManager.UnloadSceneAsync("SceneA");
SceneManager.LoadScene("SceneB");

C

StartCoroutine(UnloadThenLoad());

IEnumerator UnloadThenLoad()
{
    yield return SceneManager.UnloadSceneAsync("SceneA");
    SceneManager.LoadScene("SceneB");
}

D

SceneManager.UnloadScene("SceneA");
SceneManager.LoadSceneAsync("SceneB");

💡 Hint

Think about waiting for the unload operation to finish before loading.

Yielding the AsyncOperation returned by UnloadSceneAsync waits until unloading finishes before loading the next scene.

Practice

1. What does loading a scene in Unity do?

easy

A. It changes what the player sees by switching or adding scenes.

B. It deletes all game objects permanently.

C. It saves the current game progress automatically.

D. It pauses the game without changing the view.

Solution

1. Step 1: Understand scene loading purpose

   Loading a scene changes the visible content by switching or adding new scenes.

2. Step 2: Compare other options

   Deleting objects, saving progress, or pausing are unrelated to scene loading.

3. Final Answer:

   It changes what the player sees by switching or adding scenes. -> Option A

4. Quick Check:

   Scene loading = change visible scenes [OK]

Hint: Loading scenes changes what player sees [OK]

Common Mistakes:

• Confusing loading with saving game progress
• Thinking loading deletes objects
• Assuming loading pauses the game

2. Which of the following is the correct syntax to load a scene additively in Unity using C#?

easy

A. SceneManager.LoadScene("Level2", LoadSceneMode.Additive);

B. SceneManager.LoadSceneAdditive("Level2");

C. SceneManager.LoadScene("Level2", true);

D. SceneManager.AddScene("Level2");

Solution

1. Step 1: Recall Unity scene loading syntax

   The correct method is LoadScene with scene name and LoadSceneMode.Additive as parameters.

2. Step 2: Check each option

   Only SceneManager.LoadScene("Level2", LoadSceneMode.Additive); uses the correct method and enum for additive loading.

3. Final Answer:

   SceneManager.LoadScene("Level2", LoadSceneMode.Additive); -> Option A

4. Quick Check:

   LoadScene + LoadSceneMode.Additive = correct syntax [OK]

Hint: Use LoadScene with LoadSceneMode.Additive [OK]

Common Mistakes:

• Using non-existent methods like LoadSceneAdditive
• Passing boolean instead of LoadSceneMode enum
• Confusing AddScene with LoadScene

3. What will happen if you run this code snippet in Unity?

SceneManager.LoadScene("Menu");
SceneManager.LoadScene("Game", LoadSceneMode.Additive);

medium

A. Only the "Game" scene will be loaded, replacing "Menu".

B. Only the "Menu" scene will be loaded, ignoring the second call.

C. Both "Menu" and "Game" scenes will be loaded together.

D. An error will occur because you cannot load two scenes in a row.

Solution

1. Step 1: Understand default and additive loading

   The first call loads "Menu" scene normally (single mode), replacing current scenes. The second call loads "Game" additively, adding it without unloading "Menu".

2. Step 2: Analyze the sequence

   Since the second call uses additive mode, both scenes "Menu" and "Game" will be loaded together.

3. Final Answer:

   Both "Menu" and "Game" scenes will be loaded together. -> Option C

4. Quick Check:

   Additive loading adds scene without unloading [OK]

Hint: Additive mode loads scene without unloading others [OK]

Common Mistakes:

• Assuming first load is replaced by second always
• Thinking additive unloads previous scenes
• Believing multiple loads cause errors

4. Identify the error in this Unity C# code for unloading a scene:

SceneManager.UnloadScene("Level1");

medium

A. UnloadScene is deprecated; use UnloadSceneAsync with scene name.

B. UnloadSceneAsync should be used instead of UnloadScene.

C. There is no error; the code unloads the scene correctly.

D. UnloadScene requires a Scene object, not a string.

Solution

1. Step 1: Check Unity API for unloading scenes

   SceneManager.UnloadScene requires a Scene object as parameter, not a string name. No overload accepts string directly.

2. Step 2: Analyze the code

   The code will not compile. Correct usage: Scene scene = SceneManager.GetSceneByName("Level1"); SceneManager.UnloadScene(scene);

3. Final Answer:

   UnloadScene requires a Scene object, not a string. -> Option D

4. Quick Check:

   UnloadScene(Scene), not (string) [OK]

Hint: UnloadScene requires Scene object, not string [OK]

Common Mistakes:

• Passing string name instead of Scene object
• Thinking UnloadScene is deprecated
• Assuming the code runs without error

5. You want to load a new scene "Battle" without unloading the current "Town" scene, but only if "Battle" is not already loaded. Which code snippet correctly does this in Unity?

hard

A. SceneManager.UnloadSceneAsync("Town");
SceneManager.LoadScene("Battle");

B. if (!SceneManager.GetSceneByName("Battle").isLoaded) {
SceneManager.LoadScene("Battle", LoadSceneMode.Additive);
}

C. SceneManager.LoadScene("Battle", LoadSceneMode.Single);

D. SceneManager.LoadScene("Battle");

Solution

1. Step 1: Check if "Battle" scene is already loaded

   Use SceneManager.GetSceneByName("Battle").isLoaded to verify if scene is loaded.

2. Step 2: Load "Battle" additively if not loaded

   If not loaded, call LoadScene with LoadSceneMode.Additive to keep "Town" scene loaded.

3. Final Answer:

   if (!SceneManager.GetSceneByName("Battle").isLoaded) { SceneManager.LoadScene("Battle", LoadSceneMode.Additive); } -> Option B

4. Quick Check:

   Check loaded + additive load = correct approach [OK]

Hint: Check isLoaded before additive load [OK]

Common Mistakes:

• Loading scene in single mode, unloading current scene
• Not checking if scene is already loaded
• Unloading current scene before loading new one