A simple way to add Behaviour to a GUITexture in Unity3D on a Swipe Touch event using the FingerGestures plugin.

swiper.cs

using UnityEngine;
using System.Collections;

public class Swiper : MonoBehaviour {
  
  public GameObject appController; // some controller object that handles your app behaviour
  public GUITexture swipeObject;   // the GUITexture you want to add swipe behaviour to
  
  // Note: this relies on the slick little FingerGestures library on the Unity Asset Store: http://u3d.as/content/william-ravaine/finger-gestures/21Z
  
  void OnEnable() {
    FingerGestures.OnFingerSwipe += FingerGestures_OnFingerSwipe;
  }
  
  void OnDisable() {
    FingerGestures.OnFingerSwipe -= FingerGestures_OnFingerSwipe;
  }
  
  void FingerGestures_OnFingerSwipe( int fingerIndex, Vector2 startPos, FingerGestures.SwipeDirection direction, float velocity ) {
    if(swipeObject.HitTest(startPos)) {
      if(direction == FingerGestures.SwipeDirection.Left) {
        // in AppController.cs you can implement the behaviour, or just do it here
        appController.SendMessage("doSomethingLeft"); 
      }
  
      if(direction == FingerGestures.SwipeDirection.Right) {
        // in AppController.cs you can implement the behaviour, or just do it here
        appController.SendMessage("doSomethingRight"); 
      } 
    } 
  }
}