Stopping coroutines in Unity - Mini Project: Build & Apply

Stopping coroutines

📖 Scenario: You are making a simple Unity game where an object moves up and down repeatedly using a coroutine. You want to learn how to stop this movement when the player presses a key.

🎯 Goal: Build a Unity script that starts a coroutine to move an object up and down, then stops the coroutine when the player presses the spacebar.

📋 What You'll Learn

Create a coroutine that moves an object up and down repeatedly.

Store the coroutine in a variable to control it.

Stop the coroutine when the spacebar is pressed.

Print a message when the coroutine stops.

💡 Why This Matters

🌍 Real World

Coroutines are used in games to run tasks over time without freezing the game, like animations or timed events. Knowing how to stop them lets you control game behavior smoothly.

💼 Career

Game developers often use coroutines in Unity to manage animations, delays, and sequences. Being able to start and stop coroutines is essential for responsive and efficient game code.

1

Create the MoveUpDown coroutine

Create a coroutine method called MoveUpDown that moves the object up by 1 unit, waits for 1 second, moves it down by 1 unit, and waits for 1 second in a loop.

Unity

using UnityEngine;

public class MoveObject : MonoBehaviour
{
    void Start()
    {
        // Your code here
    }

    // Create the MoveUpDown coroutine here
    // Your code here
}

Need a hint?

Use IEnumerator to create the coroutine method. Use a while (true) loop to repeat the movement.

2

Start the coroutine and save it

In the Start method, start the MoveUpDown coroutine and save it in a variable called moveCoroutine of type Coroutine.

Unity

using UnityEngine;
using System.Collections;

public class MoveObject : MonoBehaviour
{
    Coroutine moveCoroutine;

    void Start()
    {
        // Start the MoveUpDown coroutine and save it in moveCoroutine
        // Your code here
    }

    IEnumerator MoveUpDown()
    {
        while (true)
        {
            transform.position += Vector3.up;
            yield return new WaitForSeconds(1f);
            transform.position += Vector3.down;
            yield return new WaitForSeconds(1f);
        }
    }
}

Need a hint?

Use StartCoroutine and assign it to moveCoroutine to keep a reference.

3

Stop the coroutine on spacebar press

Add an Update method that checks if the spacebar is pressed using Input.GetKeyDown(KeyCode.Space). If pressed, stop the moveCoroutine using StopCoroutine(moveCoroutine) and print "Coroutine stopped".

Unity

using UnityEngine;
using System.Collections;

public class MoveObject : MonoBehaviour
{
    Coroutine moveCoroutine;

    void Start()
    {
        moveCoroutine = StartCoroutine(MoveUpDown());
    }

    void Update()
    {
        // Stop the coroutine when spacebar is pressed
        // Your code here
    }

    IEnumerator MoveUpDown()
    {
        while (true)
        {
            transform.position += Vector3.up;
            yield return new WaitForSeconds(1f);
            transform.position += Vector3.down;
            yield return new WaitForSeconds(1f);
        }
    }
}

Need a hint?

Use Input.GetKeyDown(KeyCode.Space) to detect the spacebar press and StopCoroutine to stop the running coroutine.

4

Print confirmation when coroutine stops

Make sure the program prints "Coroutine stopped" to the console when the coroutine is stopped by pressing the spacebar.

Unity

using UnityEngine;
using System.Collections;

public class MoveObject : MonoBehaviour
{
    Coroutine moveCoroutine;

    void Start()
    {
        moveCoroutine = StartCoroutine(MoveUpDown());
    }

    void Update()
    {
        if (Input.GetKeyDown(KeyCode.Space))
        {
            StopCoroutine(moveCoroutine);
            Debug.Log("Coroutine stopped");
        }
    }

    IEnumerator MoveUpDown()
    {
        while (true)
        {
            transform.position += Vector3.up;
            yield return new WaitForSeconds(1f);
            transform.position += Vector3.down;
            yield return new WaitForSeconds(1f);
        }
    }

    // No additional code needed here
}

Need a hint?

Press the spacebar while the game is running to see the message in the console.