harvestdale-unity/Assets/Scripts/UI/HotbarUI.cs

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

public class HotbarUI : GuiPanel
{
  [SerializeField] private GameObject hotbarSlotPrefab;
  private List<HotbarSlotUI> slots = new List<HotbarSlotUI>();
  private Inventory playerInventory;
  private PlayerController playerController;
  private int hotbarSlotCount = 9;

  private void Start()
  {
    Inventory.OnPlayerInventoryChanged += UpdateSlots;
  }
  public override void OnOpen()
  {
    if (slots.Count == 0)
    {
      playerInventory = GameObject.FindGameObjectWithTag("Player").GetComponent<Inventory>();
      playerController = GameObject.FindGameObjectWithTag("Player").GetComponent<PlayerController>();
      hotbarSlotCount = playerController.hotbarSlotCount;
      CreateSlots();
    }
    UpdateSlots();
  }

  public override void OnClose()
  {
  }

  private void CreateSlots()
  {
    for (int i = 0; i < hotbarSlotCount; i++)
    {
      HotbarSlotUI newSlot = Instantiate(hotbarSlotPrefab, Vector3.zero, Quaternion.identity, transform).GetComponent<HotbarSlotUI>();
      newSlot.slotIndex = i;
      slots.Add(newSlot);
    }
  }

  private void UpdateSlots()
  {
    for (int i = 0; i < slots.Count; i++)
    {
      slots[i].SetInventoryItem(playerInventory.items[i] ?? null);
    }
  }

}