yichael_smartbowtv/Assets/BowArrow/Scripts/Bluetooth/BluetoothHolder.cs

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

public class BluetoothHolder : MonoBehaviour
{   
    bool debug = false;
    GameObject magEllipse;
    HashSet<Object> magEllipseViewers = new HashSet<Object>();
    public static BluetoothHolder ins;

    public static void Init()
    {
        if (!BluetoothHolder.ins) {
            GameObject bluetoothHolder = Resources.Load<GameObject>("Prefabs/BluetoothHolder");
            GameObject.Instantiate(bluetoothHolder);
        }
    }

    void Awake() 
    {
        if (ins)
        {
            Destroy(this.gameObject);
        } else {
            ins = this;
            DontDestroyOnLoad(this.gameObject);
        }
    }

    void Start() {
        magEllipse = this.transform.Find("test-ellipse").gameObject;
        this.transform.Find("CanvasForOpenDebug").gameObject.SetActive(debug);
        CloseDebug();
    } 

    public void ShowMagEllipse(Object viewer)
    {
        magEllipseViewers.Add(viewer);
        if (magEllipseViewers.Count == 1) magEllipse.SetActive(true);
    }

    public void HideMagEllipse(Object viewer)
    {
        magEllipseViewers.Remove(viewer);
        if (magEllipseViewers.Count == 0) magEllipse.SetActive(false);
    }

    public void openDebug() {
        ShowMagEllipse(this);
        this.transform.Find("Canvas").gameObject.SetActive(true);
        this.transform.Find("Objects").gameObject.SetActive(true);
    }

    public void CloseDebug() {
        HideMagEllipse(this);
        this.transform.Find("Canvas").gameObject.SetActive(false);
        this.transform.Find("Objects").gameObject.SetActive(false);
    }
}