Unity Timer

Run actions after a delay in Unity3D.

This library has been battle-tested and hardened throughout numerous projects, including the award-winning Pitfall Planet.

Written by Alexander Biggs + Adam Robinson-Yu.

Installation

To get the latest release of UnityTimer, head over to the Releases page and download the Timer.unitypackage file from the latest release. Then if you have a Unity project open, you can open the .unitypackage file to install the scripts into your project.

Alternatively, if you like to live on the bleeding edge, add https://github.com/akbiggs/UnityTimer.git to your packages in Unity Package Manager. However, we do not guarantee this will give you a stable version.

Basic Example

The Unity Timer package provides the following method for creating timers:

/// <summary>
/// Register a new timer that should fire an event after a certain amount of time
/// has elapsed.
/// </summary>
/// <param name="duration">The time to wait before the timer should fire, in seconds.</param>
/// <param name="onComplete">An action to fire when the timer completes.</param>
public static Timer Register(float duration, Action onComplete);

The method is called like this:

// Log "Hello World" after five seconds.

Timer.Register(5f, () => Debug.Log("Hello World"));

Motivation

Out of the box, without this library, there are two main ways of handling timers in Unity:

1. Use a coroutine with the WaitForSeconds method.
2. Store the time that your timer started in a private variable (e.g. startTime = Time.time), then check in an Update call if Time.time - startTime >= timerDuration.

The first method is verbose, forcing you to refactor your code to use IEnumerator functions. Furthermore, it necessitates having access to a MonoBehaviour instance to start the coroutine, meaning that solution will not work in non-MonoBehaviour classes. Finally, there is no way to prevent WaitForSeconds from being affected by changes to the time scale.

The second method is error-prone, and hides away the actual game logic that you are trying to express.

This library alleviates both of these concerns, making it easy to add an easy-to-read, expressive timer to any class in your Unity project.

Features

Make a timer repeat by setting isLooped to true.

// Call the player's jump method every two seconds.

Timer.Register(2f, player.Jump, isLooped: true);

Cancel a timer after calling it.

Timer timer;

void Start() {
   timer = Timer.Register(2f, () => Debug.Log("You won't see this text if you press X."));
}

void Update() {
   if (Input.GetKeyDown(KeyCode.X)) {
      Timer.Cancel(timer);
   }
}

Measure time by realtimeSinceStartup instead of scaled game time by setting useRealTime to true.

// Let's say you pause your game by setting the timescale to 0.
Time.timeScale = 0f;

// ...Then set useRealTime so this timer will still fire even though the game time isn't progressing.
Timer.Register(1f, this.HandlePausedGameState, useRealTime: true);

Attach the timer to a MonoBehaviour so that the timer is destroyed when the MonoBehaviour is.

Very often, a timer called from a MonoBehaviour will manipulate that behaviour's state. Thus, it is common practice to cancel the timer in the OnDestroy method of the MonoBehaviour. We've added a convenient extension method that attaches a Timer to a MonoBehaviour such that it will automatically cancel the timer when the MonoBehaviour is detected as null.

public class CoolMonoBehaviour : MonoBehaviour {

   void Start() {
      // Use the AttachTimer extension method to create a timer that is destroyed when this
      // object is destroyed.
      this.AttachTimer(5f, () => {
      
         // If this code runs after the object is destroyed, a null reference will be thrown,
         // which could corrupt game state.
         this.gameObject.transform.position = Vector3.zero;
      });
   }
   
   void Update() {
      // This code could destroy the object at any time!
      if (Input.GetKeyDown(KeyCode.X)) {
         GameObject.Destroy(this.gameObject);
      }
   }
}

Update a value gradually over time using the onUpdate callback.

// Change a color from white to red over the course of five seconds.
Color color = Color.white;
float transitionDuration = 5f;

Timer.Register(transitionDuration,
   onUpdate: secondsElapsed => color.r = 255 * (secondsElapsed / transitionDuration),
   onComplete: () => Debug.Log("Color is now red"));

A number of other useful features are included!

• timer.Pause()
• timer.Resume()
• timer.GetTimeRemaining()
• timer.GetRatioComplete()
• timer.isDone

A test scene + script demoing all the features is included with the package in the Timer/Example folder.

Usage Notes / Caveats

1. All timers are destroyed when changing scenes. This behaviour is typically desired, and it happens because timers are updated by a TimerController that is also destroyed when the scene changes. Note that as a result of this, creating a Timer when the scene is being closed, e.g. in an object's OnDestroy method, will result in a Unity error when the TimerController is spawned.