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, you can clone this repository into your project's Assets folder. 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. This library does not currently seem to work on the Hololens. We are looking into a solution for this.
2. 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.