Hi There!

For your entertainment and mine I created a simple script which should implement touch controls for phones (I don't have a mobile phone!)

Oh, also, whilst you 'could' use GuiText, a guiTexture is much more easier to use for mobile input (although neither is preferable!) Regardless, here's the code:

using UnityEngine;
[RequireComponent(typeof(GUITexture))]
public class UnityBasic1 : MonoBehaviour
{

private GUITexture _gui;
public Vector2 MousePosition;
private bool _buttonEnabled;//This means this button can only be 'pressed' once a frame.

void Start()
{
    transform.localScale = Vector3.zero;//for some retarded reason gui elements scale from 0 not 1.
    _gui = GetComponent<GUITexture>();
    _gui.pixelInset = new Rect(_gui.pixelInset.x, _gui.pixelInset.y, _gui.texture.width, _gui.texture.height);//make sure it's pixel perfect sized.
}
void Update()
{
    _buttonEnabled = false;//We reset the button.

    foreach (Touch touch in Input.touches)
    {
        if (_buttonEnabled) return;//don't go any further if this button is pressed.
        if (!_gui.HitTest(touch.position)) continue;//do hit test, we 'press' it??
        switch (touch.phase)
        {
            case TouchPhase.Began:
            case TouchPhase.Moved:
            case TouchPhase.Stationary:
                ButtonPressed();//We hit the button!
                return;//Return completely out of the update.
        }
    }

    //NOTE: PC TESTING
    if (_buttonEnabled) return;//don't go any further if this button is pressed.

    MousePosition = Input.mousePosition;
    if (!Input.GetMouseButton(0)) return;//Bugger off if no mouse press.
    if (!_gui.HitTest(MousePosition)) return;
    ButtonPressed(); //We hit the button!
}

private void ButtonPressed()
{
    _buttonEnabled = true;//This button has been hit.
    Debug.Log("Do incremental action here.");
}
}

how do you use this code to rotate a sphere on ios when the user drags their finger around the gui texture