Cached Camera Reference

Accessing Camera.main repeatedly incurs a performance cost because Unity perfomrs a scene-wide search by tag each time. To avoid this, maintain a single cached reference initialized on first access:

private static Camera _cachedMainCamera;

public static Camera MainCamera
{
    get
    {
        if (_cachedMainCamera == null)
            _cachedMainCamera = Camera.main;
        return _cachedMainCamera;
    }
}

Reusable WaitForSeconds Instances

Creating WaitForSeconds objects frequently triggers unnecessary heap allocations. A dictionary-based cache returns pre-allocated instances for common time values:

private static readonly Dictionary<float, WaitForSeconds> _waitCache = new Dictionary<float, WaitForSeconds>();

public static WaitForSeconds GetWait(float seconds)
{
    if (_waitCache.TryGetValue(seconds, out WaitForSeconds cached))
        return cached;

    cached = new WaitForSeconds(seconds);
    _waitCache[seconds] = cached;
    return cached;
}

UI Interaction Detection

Determine whether the current input position overlaps any UI element using Unity’s event system without allocating new collections per call:

private static readonly PointerEventData _pointerData = new PointerEventData(EventSystem.current);
private static readonly List<RaycastResult> _raycastResults = new List<RaycastResult>();

public static bool IsInputOverUI()
{
    _pointerData.position = Input.mousePosition;
    _raycastResults.Clear();
    EventSystem.current.RaycastAll(_pointerData, _raycastResults);
    return _raycastResults.Count > 0;
}

Canvas Element World Position Conversion

Convert a RectTransform from canvas space to world coordinates using RectTransformUtility:

public static Vector3 WorldPositionFromCanvasElement(RectTransform element)
{
    RectTransformUtility.ScreenPointToWorldPointInRectangle(
        element,
        element.position,
        MainCamera,
        out Vector3 worldPos);
    return worldPos;
}

Efficient Child GameObject Cleanup

Extend Transform with a method that safely destroys all immediate child game objects in one operation:

public static void ClearChildren(this Transform parent)
{
    for (int i = parent.childCount - 1; i >= 0; i--)
    {
        Object.Destroy(parent.GetChild(i).gameObject);
    }
}