Selectable.FindSelectableOnLeft

Returns

Selectable The Selectable object to the left of current.

Description

Find the selectable object to the left of this one.

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // required when using UI elements in scripts

public class ExampleClass : MonoBehaviour
{
    public Button btnMain;

    public void Start()
    {
        //Finds and assigns the selectable to the left of the main button.
        Selectable newSelectable = btnMain.FindSelectableOnLeft();

        Debug.Log(newSelectable.name);
    }
}