Animation events in Unity - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output when an animation event triggers this method?

Consider the following Unity C# script attached to a GameObject with an animation that has an event calling PlaySound. What will be printed in the console when the animation event fires?

Unity

using UnityEngine;

public class AnimationEventTest : MonoBehaviour
{
    public void PlaySound()
    {
        Debug.Log("Sound played at frame " + Time.frameCount);
    }
}

A Sound played at frame [current frame count when event fires]

B Sound played at frame 0

C Sound played at frame 1

D No output, method not called

💡 Hint

Animation events call the method at the exact frame they are set in the animation timeline.

The method PlaySound is called by the animation event at the frame it is set. The output shows the frame count at that moment, which varies depending on when the event triggers during runtime.

🧠 Conceptual

intermediate

Which statement about Unity animation events is true?

Select the correct statement about animation events in Unity.

A Animation events require the method to be static.

B Animation events can call methods with one parameter of type string, float, int, or object.

C Animation events can call any method regardless of parameters.

D Animation events can only call methods with no parameters.

💡 Hint

Check Unity documentation on animation event method signatures.

Unity animation events can call methods with zero or one parameter. The parameter can be a string, float, int, or object type. Methods with multiple parameters or unsupported types cannot be called.

🔧 Debug

advanced

Why does this animation event method cause a runtime error?

Given the method below, an animation event calls TriggerEffect but the game crashes with a NullReferenceException. What is the cause?

Unity

using UnityEngine;

public class EffectTrigger : MonoBehaviour
{
    private ParticleSystem effect;

    public void TriggerEffect()
    {
        effect.Play();
    }
}

A ParticleSystem.Play() cannot be called from animation events.

B The method signature is invalid for animation events.

C The ParticleSystem variable 'effect' is never assigned, so it is null when Play() is called.

D The method must be static to be called by animation events.

💡 Hint

Check if all variables used in the method are properly initialized.

The private variable 'effect' is never assigned a ParticleSystem instance, so it is null. Calling Play() on null causes a NullReferenceException at runtime.

📝 Syntax

advanced

Which method signature is valid for an animation event with a float parameter?

Choose the correct method signature that can be called by an animation event passing a float value.

A public void SetSpeed(float speed, int multiplier)

B private void SetSpeed(float speed)

C public float SetSpeed(float speed)

D public void SetSpeed(float speed)

💡 Hint

Animation event methods must be public and have zero or one parameter.

Animation event methods must be public, return void, and accept zero or one parameter of supported types. Option D meets all these requirements.

🚀 Application

expert

How to pass a string parameter via animation event and use it in the method?

You want to trigger a method via animation event that receives a string parameter to display a message. Which code snippet correctly implements this?

Unity

using UnityEngine;

public class MessageDisplay : MonoBehaviour
{
    public void ShowMessage(string message)
    {
        Debug.Log("Message: " + message);
    }
}

A Add an animation event calling ShowMessage with the string parameter set in the animation timeline.

B Add an animation event calling ShowMessage with no parameters and set the message inside the method.

C Add an animation event calling ShowMessage but pass an int parameter instead of string.

D Add an animation event calling ShowMessage with multiple parameters separated by commas.

💡 Hint

Animation events allow passing one parameter of type string, float, int, or object.

To pass a string parameter, set the parameter value in the animation event inspector and ensure the method accepts a single string parameter. Option A correctly describes this.