A easy to use timer class. With multiple events that can be used. There is an editor script that inhance the usage of the timer class.

Writen by - Bas

Methods	Return	Description
+ ResetTimer	void	Reset the timer to startingTime and calls the onReset event
+ SetCanCount(bool)	void	Set the canCount property, when setting it to true it will start counting, otherwise is stops
+ SetTimerLenght(float)	void	Set the timer lenght, when resetting it will use this number
+ GetCurrentTimerLenght	float	Get the timer it's current lenght
+ GetCurrentTimerPercentage	float	Calculates the percentage of the current timer relative to the progress. Return a number between 0-1
+ ToggleTimerLengthPreference	void	Toggles the current timer to the big lenght if previously was small, otherwise in reverse
- Counting	void	The function that counts the timer. Calls events when it's needs to

Events	Description
onTimerDone	An event for when the timer is done with counting
onTimerPassedThreshold	An event for when the timer is has passed the threshold when counting up
onStart	An event for when starting counting
onReset	An event for when reseting the timer

Timer class Unity inspector

You want to see how it works Timer.cs, there is also a custom editor script for it. Also a sctruct for timer data.