GUIUtility.GetControlID  

static function GetControlID (focus : FocusType) : int

static function GetControlID (hint : int, focus : FocusType) : int

static function GetControlID (contents : GUIContent, focus : FocusType) : int

static function GetControlID (focus : FocusType, position : Rect) : int

static function GetControlID (hint : int, focus : FocusType, position : Rect) : int

static function GetControlID (contents : GUIContent, focus : FocusType, position : Rect) : int

Description

Get a unique ID for a control.

// Prints a not used ID that can be assigned to a control

function OnGUI() {
    // Gets a ID for a control that cannot receive keyboard focus (A button)
    Debug.Log("Available id: " + GUIUtility.GetControlID(FocusType.Passive));
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void OnGUI() {
        Debug.Log("Available id: " + GUIUtility.GetControlID(FocusType.Passive));
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def OnGUI():
        Debug.Log(('Available id: ' + GUIUtility.GetControlID(FocusType.Passive)))