how to writer a Delayer?

I want to write a Function or calss to to achieve delay function!how ?

You don't need to write anything; use yield WaitForSeconds.

I agree with the yield function but if for whatever reason you need to have a delayer you can use this...

NOTE: this is in C#

float timelapse = 0f;
float DelayTime = 10f;   // Delays for 10 sec

void Update(){
    timelapse  = Time.deltaTime;

    if (timelapse  >= DelayTime)
       {
            timeLapse = 0f;

            // Call your function here
            myFunction();
       }

}