Unity3D: Error when creating Grid layout with List<Transfrom>

Question

Unity3D 2018.2

Problem: Grid not being populated by list, not responding correctly to the List<> being filled with Transforms, contains at least 1 item in List<> so it should not be empty. Something is not being transferred right

I'm trying to create a Grid Layout in a scroll view, which is filled with buttons containing transforms kept in a List<>

I get the transforms from checking a GameObject which will usually have 0-25 child transforms in it.

Once it gets all the child transforms from the parent's GameObject, check which child has a tag called "Satellite". After fill the Grid with the List<> containing those certain gameObject.transforms.

Clicking the buttons in the grid should contain the transform, for example OnMouseEnter() in the script if I use Debug.Log(transform.name) it should display it.

Here is the code I'm using which contain no errors, the grid is empty so I'm not receiving the transforms correctly but I don't know what is wrong with the code. Thank you for the help.

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

public class SatelliteGridControl : MonoBehaviour {

private List<Transform> satelliteListFromPlanet;

[SerializeField]
private GameObject buttonTemplate;
[SerializeField]
private GridLayoutGroup gridGroup;
[SerializeField]
private Sprite[] iconSprites;

// Use this for initialization
void OnEnable()
{
    getSatellitesInPlanet();

    satelliteListFromPlanet = new List<Transform>();

    for (int i = 1; i <= satelliteListFromPlanet.Count; i++)
    {
        SatTransfrom newSatellite = new SatTransfrom();
        newSatellite.iconSprite = iconSprites[Random.Range(0, iconSprites.Length)];

        satelliteListFromPlanet.Add(newSatellite);
    }

    GenInventory();
}

//  Get Satellites
private void getSatellitesInPlanet()
{
    satelliteListFromPlanet = new List<Transform>();

    //  Get current planet
    Transform currentPlanet = GameObject.FindGameObjectWithTag("MainCamera").GetComponent<HandleCamera>().targetToLookAt;

    //  Check inside for satellites
    foreach (Transform satellite in currentPlanet)
    {
        //  Check transform for tag
        if (satellite.CompareTag("Satellite"))
        {
            //  Add each transform from planet to array
            satelliteListFromPlanet.Add(satellite);
        }
    }
}

//  Handle Grid
private void GenInventory()
{
    if (satelliteListFromPlanet.Count < 6)
    {
        gridGroup.constraintCount = satelliteListFromPlanet.Count;
    }
    else
    {
        gridGroup.constraintCount = 5;
    }

    foreach (SatTransfrom sat in satelliteListFromPlanet)
    {
        GameObject newButton = Instantiate(buttonTemplate) as GameObject;
        newButton.SetActive(true);

        newButton.GetComponent<SatelliteButton>().SetIcon(sat.iconSprite);
        newButton.transform.SetParent(buttonTemplate.transform.parent, false);
    }
 }

 public class SatTransfrom : Transform
 {
    public Sprite iconSprite;
 }
}

Answer 1

In OnEnable you first call getSatellitesInPlanet to populate your list satelliteListFromPlanet.

But right after you finished you call

satelliteListFromPlanet = new List<Transform>();

Which resets your list to a new empty one.

Than you have a loop

for (int i = 1; i <= satelliteListFromPlanet.Count; i++)
{ //... }

But since satelliteListFromPlanet is an empty list at this moment nothing happens.

And finally when you call GetInventory your list is still empty so

foreach (SatTransfrom sat in satelliteListFromPlanet)

Is executed never since there are no elements in satelliteListFromPlanet.

---

Now to the second problem:

You have

for(int i = 0; i< sateliteLostFromPlanet.Count; i++)

But inside of this loop you do

sateliteListFromPlanet.Add(xy);

... So what happens to your List during running this loop?

It grows bigger 1 elememt each loop so your loop condition i < sateliteListFromPlanet.Count will allways be true since after every execution your list is 1 element longer and i is 1 bigger!

Result: You add more and more elements to the same list "forever" until your device runs out of memory.