using UnityEngine;
using System.Collections;

public class Labels : MonoBehaviour {
  bool showLabel = false;
  bool firstLabel = false;
  // Use this for initialization
  void Start () {
   
  }
   
  // Update is called once per frame
  void Update () {
   
  }
  void OnGUI() {

   if (GUI.Button (new Rect (10, 70, 50, 30), "Click"))
   {
    showLabel = true;
    if (firstLabel == true)    firstLabel = false;
    else firstLabel = true;

   }

   if (showLabel)
   {
    if (firstLabel == true)
    {
     GUI.Label (new Rect (10, 10, 100, 20), "Hello World 1");

    }
     else
    {
     GUI.Label (new Rect (10, 10, 100, 20), "Hello World 2");

    }
   }

  }
}