Custom editor add sprite to game object with sprite renderer

Questions & Answers
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1 
~~~~~
private Sprite[] t_noteSprites;

private void OnEnable()
{
    t_noteSprites = new Sprite[6];
    t_noteSprites[0] = Resources.Load<Sprite>("pathway");
    ~~~
}
~~~~
public override void OnInspectorGUI()
{
~~~
    if (GUILayout.Button("Apply Sprite of Child Object"))
    {
        ApplyChildNoteObjectSprite(noteObject);
    }
~~~
}
~~~
private void ApplyChildNoteObjectSprite(NoteObject noteObject)
{
    // Check sprite's existence and adjust it
    for (int i = 0; i < noteObject.transform.childCount; i++)
    {
        Transform child = noteObject.transform.GetChild(i);

        SpriteRenderer spriteRenderer = child.GetComponent<SpriteRenderer>();

        if (spriteRenderer == null)
        {
            spriteRenderer = child.gameObject.AddComponent<SpriteRenderer>().GetComponent<SpriteRenderer>();
        }

        spriteRenderer.sprite = t_noteSprites[(int)noteObject.typeOfNote];
    }
}
~~~

In my code, if button pressed then sprite supposed to be added in spriteRenderer in GameObject; But it doen’ttttttttt.
Could you help me??