Unity3D: Grid Layout Group - add cells in runtime

Trabla:  Unity3D:  Grid Layout Group - add cells in runtime

Solving Overview:

1. We need to create Container for cells ( e.g. panel )
2. Container: Add component Grid Layout Group - setup fixed rows or cols / leave auto
3. Container: Add script with public property for cell prefab
+ code to create (clone) instances from prefab in runtime

4. We need to create cell prefab - e.g. UI.Image or UI.Button
5. Cell Prefab: Add Layout Element component

6. Set reference in Container Script to Cell Prefab



Solving:

1.Create new project 2D
Right mouse click on "Main Camera" ( "Hierarchy" view ), select UI -> Panel
- Unity will create objects - "Canvas"  with child object "Panel"

2. Click on "Panel" - in "Inspector" view click "Add Component"
- select "Layout"->"Grid Layout Group"

3. Create script for panel - select "panel" - Add Component -> "New Script" type script name
e.g. "PanelScript"

Open script in Code Editor and paste following code:

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
using UnityEngine.Events;

public class PanelScript : MonoBehaviour {

    //We will put here reference to prefab in Editor
    public GameObject CellPrefab;


    // Use this for initialization
    void Start () {
   
        for (int i=0; i < 6; i++) {
       
            GameObject newCell = Instantiate (CellPrefab) as GameObject;

            //If you add script to cell prefab
            // you can init public vars like this
            //CellScript cellScript = newCell.GetComponent<CellScript>();
            //cellScript.value1 = 1;
            //cellScript.value2 = "trololo";
            //etc.

            newCell.transform.SetParent(  this.gameObject.transform,  false);

        }


    }
   
    // Update is called once per frame
    void Update () {
   
    }
}



4. Right mouse click on "Panel"  -  UI->Image
 Now download image below and put it into "Assets" ("Project" view ) folder ( drag-n-drop image into assests )

5. Select "Image" in "Hierarchy" view and in "Inspector"
find field "Image"->"Source Image".
Drag and drop image from assets into field "Source Image" ( it displays "None(Sprite)" )

6.  In Inspector click "Add Component" - select "Layout"->"Layout Element"

7. In "Hierarchy" view  select and drag-n-drop "Image" element into "Project"->"Assests"
- Unity will create prefab "Image".
Delete "Image" object from "Hierarchy" - left click + delete button

8. Set reference in Container Script (Panel) to Cell Prefab (Image).

Hooray!!! Now run in editor.

To set fixed column or row size - select "Panel" - in "Grid Layout Group" component look at
"Constraint" properties