Component Lifecycle

Component lifecycle callbacks separate initialization, fixed simulation, frame updates, rendering, activation, and cleanup.

Callback order

For an active component, the lifecycle is:

1. Awake when the component attaches.
2. OnEnable when the component becomes active and enabled.
3. Start before its first fixed update, update, or render.
4. FixedUpdate zero or more times for each game update.
5. Update once for the game update.
6. LateUpdate after regular updates.
7. Render during drawing.
8. OnDisable when the component or its GameObject becomes inactive, or before destruction.
9. OnDestroy once when the component is removed or its GameObject is destroyed.

Awake, Start, and OnDestroy run once. OnEnable and OnDisable can run more than once as activation changes.

Choose the right callback

Callback	Use it for
Awake	Internal initialization that does not depend on later component configuration
OnEnable	Subscribing to events or starting work that must pause while disabled
Start	Initialization that reads other components or values assigned after AddComponent
FixedUpdate	Fixed-rate simulation
Update	Input, timers, and frame-rate-aware behavior
LateUpdate	Camera following and final transform adjustments
Render	Submitting draw commands to the active sprite batch
OnDisable	Unsubscribing or pausing active work
OnDestroy	Final component cleanup

Configuration before Start

Start is intentionally deferred, so callers can configure a component after adding it:

var follower = cameraObject.AddComponent<CameraFollower>();
follower.Target = player.Transform;
follower.Smoothing = 8f;

public sealed class CameraFollower(GameObject gameObject, Camera2D camera)
    : Component(gameObject)
{
    public Transform? Target { get; set; }
    public float Smoothing { get; set; }

    public override void Start()
    {
        ArgumentNullException.ThrowIfNull(Target);
    }

    public override void LateUpdate(double deltaTime)
    {
        var amount = 1f - MathF.Exp(-Smoothing * (float)deltaTime);
        camera.Position = Vector2.Lerp(camera.Position, Target!.Position, amount);
    }
}

Activation and cleanup

Set Enabled when one behavior should pause. Set GameObject.Active when every component on the object should pause. In both cases, inactive components skip fixed updates, updates, late updates, and rendering.

If a component subscribes in OnEnable, unsubscribe in OnDisable. Reserve OnDestroy for cleanup that happens only once. Scene unload invokes the destruction path for every remaining object before its scoped services are disposed.