C# Timer class

Timer.cs

using UnityEngine;
using System;

/* Timer class.
Example usage:

public class Mover : MonoBehaviour {

	public Vector3 startPosition;
	public Vector3 endPosition;
	public Timer timer = new Timer();

	void Start () {
		// Set timer so we move from startPosition to endPosition over 1 second
		timer.SetNewDuration(1f);

		// note: if you want to keep moving even if Unity's Time.timeScale is 0, set `timer.useUnscaledTime = true`;
	}

	void Update () {
		transform.position = Vector3.Lerp(startPosition, endPosition, timer.PercentageDone);
		if (timer.IsDone) {
			Debug.Log("Finished moving!");
		}
	}
}

*/

[System.Serializable]
public class Timer {

	public bool useUnscaledTime;
	[SerializeField] private float startTime;
	[SerializeField] private float endTime;
	[SerializeField] private float duration;

	// Set a new duration, effectively resetting the timer
	public void SetNewDuration (float newDuration) {
		if (newDuration == 0f) {
			Debug.LogWarning("WARNING: Timer's new duration is 0");
		}
		duration = newDuration;
		startTime = this.Time;
		endTime = startTime + duration;
	}

	// Get the percentage done, helpful for Lerp methods
	public float PercentageDone {
		get {
			return Mathf.InverseLerp(startTime, endTime, this.Time);
		}
	}

	// Get the percentage done with a SmoothStep applied
	public float PercentageDoneSmoothStep {
		get {
			return Mathf.SmoothStep(0f, 1f, this.PercentageDone);
		}
	}
	
	// See if the current time is greater than or equal to the end time
	public bool IsDone {
		get {
			return this.Time >= endTime;
		}
	}

	// Extend the timer if needed
	public void ExtendDuration (float amount) {
		startTime += amount;
		endTime += amount;
	}

	private float Time {
		get {
			return useUnscaledTime ? UnityEngine.Time.unscaledTime : UnityEngine.Time.time;
		}
	}

}