Controlling a player using touch input on the mobile device

Question

I am new to Unity, and was following the tutorials of roll a ball.
I was to create it for both mobile and desktop and it is working but the only problem I have is that I am unable to create touch keys arrows(left,right,up,down) to control the player on the touch screen devices.

Please check my code below of controlling the player:

 using UnityEngine;
 using UnityEngine.UI;
 using System.Collections;

public class PlayerController : MonoBehaviour {
public float speed;
public Text countText;
public Texture2D button1; //button 1
public Texture2D button2; //button2
public Texture texture;

private Rigidbody rb;
private int count;
// Use this for initialization
void Start () {
    Screen.orientation = ScreenOrientation.LandscapeLeft;
    //GUITexture.texture = button1;
    rb = GetComponent<Rigidbody> ();
    count = 0;
    SetCountText ();
}

// Update is called once per frame
void FixedUpdate () {
    Screen.orientation = ScreenOrientation.LandscapeLeft;
    Screen.sleepTimeout = SleepTimeout.NeverSleep;
    if (SystemInfo.deviceType == DeviceType.Desktop) {
        float moveHorizontal = Input.GetAxis ("Horizontal");
        float moveVertical = Input.GetAxis ("Vertical");
        Vector3 movement = new Vector3 (moveHorizontal, 0.0f, moveVertical);
        GetComponent<Rigidbody>().AddForce (movement * speed * Time.deltaTime);
        if (Input.GetKey("escape"))
        {
            Application.Quit();
        }

    }//END Desktop
    else 
    {
        float moveHorizontal = Input.acceleration.x;
        float moveVertical = Input.acceleration.y;
        Vector3 movement = new Vector3 (moveHorizontal, 0.0f, moveVertical);
        GetComponent<Rigidbody>().AddForce (movement * speed * Time.deltaTime);
        if (Input.GetKeyDown(KeyCode.Escape))
        {
            Application.Quit(); 
        }
        foreach(Touch touch in Input.touches)
        {
            //Always getting error here
            if (GUITexture.HitTest(touch.position) && touch.phase !=TouchPhase.Ended)
            {
                GUITexture.texture = button2;
                transform.Translate(Vector3.right*30*Time.smoothDeltaTime);
            }else if(GUITexture.HitTest(touch.position) && touch.phase !=TouchPhase.Ended)
            {
                GUITexture.texture = button1;
            }
        }
    }
    // Building of force vector 

}

void OnTriggerEnter(Collider other)
{
    if (other.gameObject.CompareTag ("Pick Up"))
    {
        other.gameObject.SetActive(false);
        count = count + 1;
        SetCountText();
    }
}
void SetCountText()
{
    countText.text = "Count:" + count.ToString ();

}
}

Answer 1

Your trying to call HitTest directly from GUITexture like a static function but HitTest isn't a static function, you need to create a variable from GUITexture class and then call HitTest function from that object like this:

public GUITexture guiT;

if (guiT.HitTest(touch.position) && touch.phase !=TouchPhase.Ended)
{
    guiT.texture = button2;
    transform.Translate(Vector3.right*30*Time.smoothDeltaTime);
}
else if(guiT.HitTest(touch.position) && touch.phase !=TouchPhase.Ended)
{
    guiT.texture = button1;
}  

don't forget to assign guiT variable to something from the Editor.