use Update instead of Coroutines

Questions & Answers
1

I have a Prefab that gets instantiated everytime a ray (casted by a touch input) hit a gameobject that’s in the layer mask of the ray, that prefab has to move from the position (Screen.width / 2, 0) to (Screen.width / 2, Screen.Height / 2).
Originally I made it move by using a coroutine started at Start method, but after I read this https://unity3d.com/learn/tutorials/topics/performance-optimization/optimizing-scripts-unity-games?playlist=44069 I got that it would be better not to use too many coroutines to avoid GC issue.
And that is my case because I start a new coroutine for every prefab instantiated.
This is the code I used inside the coroutine to make prefab move:

var currentPos = transform.localPosition;
var t = 0f;
while (t < 1) {
	t += Time.deltaTime / timeToMove;
	transform.position = Vector3.Lerp (currentPos, endPos, t);
	yield return null;
}

The question is: How can I use that code in Update function?

2

Something along these lines should do the trick.

    public float timeToMove = 2f;

    private Vector3 startLerpPos;
    private Vector3 endLerpPos;
    private float currentLerpTime = -1f;
    private float t;

    void Update()
    {
        if (Input.touchCount > 0)
        {
            BeginLerp(Vector3.one);
        }
        Lerping();
    }

    public void BeginLerp(Vector3 destination)
    {
        startLerpPos = transform.localPosition;
        endLerpPos = destination;
        currentLerpTime = 0f;
    }

    private void Lerping()
    {
        if (currentLerpTime > timeToMove || currentLerpTime < 0f)
        {
            return;
        }
        else
        {
            currentLerpTime += Time.deltaTime;
            t = currentLerpTime / timeToMove;
            transform.position = Vector3.Lerp(startLerpPos, endLerpPos, t);
        }
    }

Just keep in mind that you should avoid “premature optimization”. Chances are, what you think is slowing things down is actually insignificant compared to other things in your code. Use the profiler to find the worst parts and spend time fixing those first.