Interactable.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;

public abstract class Interactable : MonoBehaviour
{
	[SerializeField]
    protected UnityEvent OnInteractEvent;

	public abstract void Interact();
}

InteractablePickup.cs

using UnityEngine;
using System.Collections;

[AddComponentMenu("Redemption/Interactables/Pickup")]
public class InteractablePickup : Interactable
{
	private bool isInteracting;

	[SerializeField] 
	private InventoryItem inventoryItem;

	public void Start()
	{
		isInteracting = false;
	}

	public override void Interact()
	{
		if(isInteracting) {
			return;
		}

		OnInteractEvent.Invoke();

		Debug.Log("Pickup item : " + inventoryItem.name);
		InventoryManager.instance.AddItem(inventoryItem);
		Destroy(gameObject);
	}

}

InventoryItem.cs

using UnityEngine;

[CreateAssetMenu(fileName="InventoryItem", menuName="Redemption/Inventory Item")]
public class InventoryItem : ScriptableObject {

	[SerializeField] 
	[Tooltip("Item icon that is shown in the inventory")]
	private Sprite itemIcon;

	[SerializeField] 
	[Tooltip("Item name that is shown in the tooltip")]
	private string itemName;

	[SerializeField] 
	[TextArea(3, 10)] 
	[Tooltip("Item description that is shown in the tooltip")]
	private string itemDescription;

	[SerializeField]
	[Tooltip("Gameobject to show when item is held in hand")]
	private GameObject itemHandPrefab;

	public Sprite ItemIcon {
		get {
			return itemIcon;
		}
	}

	public string ItemName {
		get {
			return itemName;
		}
	}

	public string ItemDescription {
		get {
			return itemDescription;
		}
	}

	public GameObject ItemHandPrefab {
		get {
			return itemHandPrefab;
		}
	}


}

InventoryManager.cs

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

public class InventoryManager : MonoBehaviour
{

	public static InventoryManager instance;

	[SerializeField]
	private GameObject inventory;

	[SerializeField]
	private GameObject itemSlotPrefab;

	private int inventorySize;
	
	[SerializeField]
	private int inventoryColumns;

	[SerializeField]
	private int inventoryRows;
	
	//[SerializeField]
	private Image[] itemImages;

	[SerializeField]
	private InventoryItem[] items;

	private bool inventoryActive;

	public bool InventoryActive {
		get {
			return inventoryActive;
		}
	}

	void Start ()
	{
		inventoryActive = false;
		inventory.SetActive(false);

		instance = this;
	}

	void Update()
	{
	}
	
	public void AddItem(InventoryItem item)
	{
		for(int i = 0; i < inventorySize; i++) {
			if(items[i] == null) {
				items[i] = item;
				itemImages[i].sprite = item.ItemIcon;
				itemImages[i].enabled = true;
				return;
			}
		}
	}

	public void RemoveItem(InventoryItem item)
	{
		for(int i = 0; i < inventorySize; i++) {
			if(items[i] == item) {
				items[i] = null;
				itemImages[i].sprite = null;
				itemImages[i].enabled = false;
				return;
			}
		}
	}
}