How can i add a new item in dropdown options ?

using UnityEngine; using System.Collections; using UnityEngine.UI; using System.Collections.Generic; using System.IO.Ports;

public class dd_Menu : MonoBehaviour {

 public Dropdown     Maindropdown;
 public Text         text;
 public string[]     ports;
 public static SerialPort sp = new SerialPort ("COM1",9600);// Refrence to serialPort 

 void Start () {

     // Fill ports array with COM's Name available
     ports = SerialPort.GetPortNames ();

     //clear/remove all option item
     Maindropdown.options.Clear ();

     //fill the dropdown menu OptionData with all COM's Name in ports[]
     foreach (string c in ports) 
     {
         Maindropdown.options.Add (new Dropdown.OptionData() {text=c});
     }

     //this swith from 1 to 0 is only to refresh the visual DdMenu
     Maindropdown.value = 1;
     Maindropdown.value = 0;
 }
 
 void Update () {
 
     //COM port Name that is currently selected on the dropDown Menu
     text.text = ports [Maindropdown.value];
 }

} Hey anis i use this script for my ports i think you will find every think you need in it . if you want to make the .clear() work with OnClick event you have to create another button/toggle and affect this function to it .