Singleton Pattern In Unity

A singleton is a class that allows only one instance of itself to exist. Any script can access it from anywhere without needing a reference.

• Only one instance exists in the game
• Accessible from any script using ClassName.Instance
• Persists across scenes (optional)

Basic Singleton Implementation

This is the simplest singleton pattern.

public class GameManager : MonoBehaviour
{
    public static GameManager Instance;
    void Awake()
    {
        Instance = this;
    }
    public void StartGame()
    {
        Debug.Log("Game Started");
    }
}

Now any script can call GameManager.Instance.StartGame() without finding or dragging references.

Complete Singleton (No Duplicates)

This version prevents duplicate instances from being created.

public class AudioManager : MonoBehaviour
{
    public static AudioManager Instance;
    void Awake()
    {
        if (Instance == null)
        {
            Instance = this;
        }
        else
        {
            Destroy(gameObject);  // Destroy duplicate
        }
    }
    public void PlaySound(AudioClip clip)
    {
        AudioSource.PlayClipAtPoint(clip, Vector3.zero);
    }
}

If a second AudioManager tries to spawn, it destroys itself. The first one remains.

Using Singleton from Any Script

Once you have a singleton, any script can access it directly. This is the main benefit - no dragging references in Inspector.

public class Player : MonoBehaviour
{
    void OnTriggerEnter(Collider other)
    {
        if (other.CompareTag("Coin"))
        {
            GameManager.Instance.AddScore(10);
            AudioManager.Instance.PlayCoinSound();
        }
    }
}

No need to drag references. Just call ClassName.Instance.MethodName() from anywhere.

Singleton vs Static Class

When to Use Singleton

• Good for: GameManager, AudioManager, ScoreManager, UIManager, SaveSystem.
• Not Good For: Player (if multiple players), Enemies, Bullets, Items.