Unity Timer Example (Author : Chatchai Saratakij (Ton))

Timer.cs

using UnityEngine;
using System.Collections;

public sealed class Timer : MonoBehaviour {

	[SerializeField]
	[Range(0, 600)]
	[Tooltip("Time in seconds. (Time between 0 seconds to 10 minutes.)")]
	int time;

	int minuteTime;
	int secondsTime;
	bool isStarted;
	bool isTimesUp;

	public int CurrentTime { get { return time; } }
	public int CurrentTimeInMinute { get { return minuteTime; } }
	public int CurrentTimeInSeconds { get { return secondsTime; } }
	public bool IsStarted { get { return isStarted; } }
	public bool IsTimesUp { get { return isTimesUp; } }

	public Timer() {
		time = 60;
		minuteTime = time / 60;
		secondsTime = time % 60;
		isStarted = isTimesUp = false;
	}

	void Start() {
		StartCoroutine("Countdown");
	}

	IEnumerator Countdown () {
		while (!isTimesUp) {
			if (isStarted) {
				time = (time > 0) ? time - 1 : 0;
				minuteTime = time / 60;
				secondsTime = time % 60;
				isTimesUp = (time == 0) ? true : false;
			}
		yield return new WaitForSeconds(1f);
		}
	}

	public void SetStart(bool isStart) {
		isStarted = isStart;
	}
}