SwipeManager.cs

using UnityEngine;
using System.Collections;

public class SwipeManager : MonoBehaviour
{
    private float startTime;
    private Vector2 startPos;
    private bool couldBeSwipe;
    public float comfortZone;
    public float minSwipeDist;
    public float maxSwipeTime;

    void Update ()
    {
        if (iPhoneInput.touchCount > 0) {
            iPhoneTouch touch = iPhoneInput.touches [0];

            switch (touch.phase) {
            case iPhoneTouchPhase.Began:
                couldBeSwipe = true;
                startPos = touch.position;
                startTime = Time.time;
                break;
            case iPhoneTouchPhase.Moved:
                if (Mathf.Abs (touch.position.y - startPos.y) > comfortZone) {
                    couldBeSwipe = false;
                }
                break;
            case iPhoneTouchPhase.Stationary:
                couldBeSwipe = false;
                break;
            case iPhoneTouchPhase.Ended:
                float swipeTime = Time.time - startTime;
                float swipeDist = (touch.position - startPos).magnitude;

                if (couldBeSwipe && (swipeTime < maxSwipeTime) && (swipeDist > minSwipeDist)) {

                    // It's a swiiiiiiiiiiiipe!
                    float swipeDirection = Mathf.Sign (touch.position.y - startPos.y);
                    // Do something here in reaction to the swipe.
                    Debug.Log (swipeDirection);
                }
                break;
            }
        }
    }
}