A template for basic single-touch handling in Unity.

TouchController.cs

using UnityEngine;

public class TouchController : MonoBehaviour
{
    int _activeFinger = -1;

    void Update ()
    {
        ReadTouches();
    }

    void ReadTouches ()
    {
        // Iterate through each touch
        foreach (Touch touch in Input.touches)
        {
            // If we have no active touch and one is starting, set it to active
            if (_activeFinger < 0 && TouchPhase.Began == touch.phase)
            {
                _activeFinger = touch.fingerId;
                HandleTouch(touch);
                return;
            }
            // If this is the active touch, handle it
            if (_activeFinger == touch.fingerId)
            {
                HandleTouch(touch);
                // Reset _activeFinger is the touch is ending
                if (TouchPhase.Canceled == touch.phase || TouchPhase.Ended == touch.phase)
                    _activeFinger = -1;
                return;
            }
        }
    }

    void HandleTouch (Touch touch)
    {
        // Do whatever you need to do with the touch
    }
}

This is a template class for basic single-touch detection/handling in Unity. It functions by cacheing the currently active Touch ID and discarding any other touches throughout the lifetime of the touch.

I don't use a switch statement as in this situation only one touch should be used each frame; so instead I try to filter out the two cases via normal if statements (no active touch, new touch object / active touch, correct touch object) and handle those cases accordingly.

The same principal could be used for handling multiple touches or gestures by updating it to use a Switch statement and storing finger ID's and associated touch data in a dictionary. If there is any interest I can post another gist (or update this one) to show an implementation of this as well. :)