Loading screens with coroutines in Unity

Introduction

Loading screens help users know the game is working while content loads. Coroutines let us pause and wait without freezing the game.

When loading a new game level that takes time

When downloading data or assets in the background

When you want to show progress or animation during loading

When you want to keep the game responsive while waiting

When you want to delay actions without blocking the main game

Syntax

Unity

IEnumerator LoadSceneWithLoadingScreen() {
    // Show loading screen
    loadingScreen.SetActive(true);
    // Start loading scene asynchronously
    AsyncOperation asyncLoad = SceneManager.LoadSceneAsync("SceneName");
    // Wait until loading is done
    while (!asyncLoad.isDone) {
        // Optionally update progress bar here
        yield return null;
    }
    // Hide loading screen
    loadingScreen.SetActive(false);
}

Coroutines use IEnumerator and yield return to pause execution.

Use AsyncOperation to load scenes without freezing the game.

Examples

This coroutine waits 2 seconds before continuing.

Unity

IEnumerator SimpleWait() {
    Debug.Log("Start waiting");
    yield return new WaitForSeconds(2f);
    Debug.Log("Waited 2 seconds");
}

This coroutine loads a scene and logs progress until done.

Unity

IEnumerator LoadSceneAsync() {
    AsyncOperation asyncLoad = SceneManager.LoadSceneAsync("Level1");
    while (!asyncLoad.isDone) {
        Debug.Log($"Loading progress: {asyncLoad.progress * 100}%");
        yield return null;
    }
    Debug.Log("Loading complete");
}

Sample Program

This Unity script shows a loading screen with a progress bar while loading a scene called "SampleScene". It uses a coroutine to update the progress bar smoothly and only hides the loading screen after the scene is ready.

Unity

using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

public class LoadingScreenController : MonoBehaviour {
    public GameObject loadingScreen;
    public Slider progressBar;

    public void StartLoading() {
        StartCoroutine(LoadSceneWithLoadingScreen());
    }

    IEnumerator LoadSceneWithLoadingScreen() {
        loadingScreen.SetActive(true);
        AsyncOperation asyncLoad = SceneManager.LoadSceneAsync("SampleScene");
        asyncLoad.allowSceneActivation = false;

        while (!asyncLoad.isDone) {
            float progress = Mathf.Clamp01(asyncLoad.progress / 0.9f);
            progressBar.value = progress;

            if (asyncLoad.progress >= 0.9f) {
                progressBar.value = 1f;
                asyncLoad.allowSceneActivation = true;
            }

            yield return null;
        }

        loadingScreen.SetActive(false);
    }
}

Important Notes

Always activate and deactivate the loading screen GameObject to show or hide it.

Use asyncLoad.allowSceneActivation = false to control when the scene switches.

Update UI elements like progress bars inside the coroutine for smooth feedback.

Summary

Loading screens keep users informed during long waits.

Coroutines let you wait without freezing the game.

Use AsyncOperation with coroutines to load scenes smoothly.