unity | Create and destroy Jostick dynamically with touch - unity3d

Question

I want to make a jostick that created (Instatiated or whatever) in touch position(Input.getTouch(i).position) and destroyed when user doesn't touch the screen anymore. This is the source code below. Please give me an idea how to do it. Thank you.
using UnityEngine;
using System.Collections;
public class joy : MonoBehaviour
{
public GameObject joystick; //Self explanitory
public GameObject bg; //Background object for the joystick boundaries
public const float deadzone = 0f; //Deadzone for the joystick
public const float radius = 2.0f; //The radius that the joystick thumb is allowed to move from its origin
public Camera cam;
protected Collider joyCol;
protected int lastfingerid = -1; //Used for latching onto the finger
public Vector2 position = Vector2.zero;
void Awake ()
{
joyCol = bg.GetComponent<Collider>();
}
public void Disable ()
{
gameObject.active = false; //Turns off the joystick when called
}
public void ResetJoystick () //Called when the joystick should be moved back to it's original position (relative to parent object)
{
lastfingerid = -1;
joystick.transform.localPosition = Vector3.zero;
}
void Update ()
{
if (Input.touchCount == 0)
{
ResetJoystick (); //I would have figured this would be obvious? :P
}
else
{
for (int i=0; i < Input.touchCount; i++)
{
Touch touch = Input.GetTouch(i);
bool latchFinger = false;
if (touch.phase == TouchPhase.Began) //When you begin the touch, the code here gets called once
{
//Vector3 touchpos = Input.GetTouch(i).position;
//touchpos.z = 0.0f;
//Vector3 createpos = cam.ScreenToWorldPoint(touchpos);
Ray ray = cam.ScreenPointToRay (touch.position); //Creates a ray at the touch spot
RaycastHit hit; //Used for determining if something was hit
//joystick = (GameObject)Instantiate(Resources.Load("Type3/joystick"),createpos, Quaternion.identity);
//bg = (GameObject)Instantiate(Resources.Load("Type3/Bg"),createpos, Quaternion.identity);
if (joyCol.Raycast(ray,out hit,Mathf.Infinity)) //The ray hit something...
{
if (hit.collider == joyCol) //Apparently, that ray hit your joystick
{
latchFinger = true; //This turns on and sets off a chain reaction
}
}
}
if (latchFinger ) //Latch finger being true turns this code on
{
if ((lastfingerid == -1 || lastfingerid != touch.fingerId))
{
lastfingerid = touch.fingerId;
}
}
if (lastfingerid == touch.fingerId) //The real meat of the code
{
Vector3 sTW = cam.ScreenToWorldPoint (new Vector3 (touch.position.x, touch.position.y, 1)); //Transforms the screen touch coordinates into world coordinates to move our joystick
joystick.transform.position = sTW; //Hurr :O
joystick.transform.localPosition = new Vector3(joystick.transform.localPosition.x,joystick.transform.localPosition.y,0);
//float xClamp = Mathf.Clamp (joystick.transform.localPosition.x, xClampMin, xClampMax); //Limit movement to the boundaries
//float yClamp = Mathf.Clamp (joystick.transform.localPosition.y, yClampMin, yClampMax);
/*float distFromCenter = Mathf.Sqrt(joystick.transform.localPosition.x*joystick.transform.localPosition.x + joystick.transform.localPosition.y*joystick.transform.transform.localPosition.y);
float actualPercent = Mathf.Clamp01(distFromCenter/radius);
float percent = Mathf.Clamp01((distFromCenter - deadzone)/(radius - deadzone));
*/
joystick.transform.localPosition = Vector3.ClampMagnitude(joystick.transform.localPosition,radius);
//joystick.transform.localPosition = new Vector3 (xClamp, yClamp, joystick.transform.localPosition.z); //Finally, the joystick moves like it should with everything in place
if (touch.phase == TouchPhase.Ended || touch.phase == TouchPhase.Canceled)
{
ResetJoystick ();
}
}
Ray touchray = cam.ScreenPointToRay (touch.position); //Creates a ray at the touch spot
//RaycastHit hit; //Used for determining if something was hit
Debug.DrawRay (touchray.origin, touchray.direction * 100, Color.yellow); //Delete this line. It's not important.
}
}
//set our position variables x and y values to the joysticks values but clamped to a percent value instead of world coords
position.x = joystick.transform.localPosition.x/radius;
position.y = joystick.transform.localPosition.y/radius;
if(position.magnitude < deadzone)
{
position.x = 0;
position.y = 0;
}
}
}