InputNavigator.cs

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
using UnityEngine.EventSystems;
 
public class InputNavigator : MonoBehaviour
{
	    EventSystem system;
	  
	    void Start()
	    {
		        system = EventSystem.current;// EventSystemManager.currentSystem;
		      
		    }
	    // Update is called once per frame
	    void Update()
	    {
		        if (Input.GetKeyDown(KeyCode.Tab))
			        {
			            Selectable next = system.currentSelectedGameObject.GetComponent<Selectable>().FindSelectableOnDown();
			          
			            if (next != null)
				            {
				              
				                InputField inputfield = next.GetComponent<InputField>();
				                if (inputfield != null)
					                    inputfield.OnPointerClick(new PointerEventData(system));  //if it's an input field, also set the text caret
				              
				                system.SetSelectedGameObject(next.gameObject, new BaseEventData(system));
				            }
			            //else Debug.Log("next nagivation element not found");
			          
			        }
		    }
}