MonoBehaviour

class in UnityEngine

Inherits from:Behaviour

Leave feedback

Suggest a change

Switch to Manual

Description

MonoBehaviour is a base class that many Unity scripts derive from.

MonoBehaviour offers life cycle functions that make it easier to develop with Unity.

MonoBehaviours always exist as a Component of a GameObject, and can be instantiated with GameObject.AddComponent. Objects that need to exist independently of a GameObject should derive from ScriptableObject instead.

A MonoBehaviour can be deleted with Object.Destroy or Object.DestroyImmediate. When the parent GameObject is destroyed all components are automatically deleted, including MonoBehaviours.

After the underlying component is destroyed, the C# object for the MonoBehaviour remains in memory until garbage is collected. A MonoBehaviour in this state acts as if it is null. For example, it returns true for a "obj == null" check. However, this class doesn't support the null-conditional operator (?.) and the null-coalescing operator (??).

When a MonoBehaviour is serialized, the value of C# fields are included according to Unity's Serialization rules. See Script Serialization for details. The serialized data also includes internal properties, such as the reference to the MonoScript that tracks the implementation class for the object.

For code samples, see the individual MonoBehaviour methods.

Note: There is a checkbox for enabling or disabling MonoBehaviour in the Unity Editor. It disables functions when unticked. If none of these functions are present in the script, the Unity Editor does not display the checkbox. The functions are:

Start()
Update()
FixedUpdate()
LateUpdate()
OnGUI()
OnDisable()
OnEnable()

Additional resources: The Deactivating GameObjects page in the manual.

Properties

destroyCancellationToken	Cancellation token raised when the MonoBehaviour is destroyed (Read Only).
didAwake	Returns a boolean value which represents if Awake was called.
didStart	Returns a boolean value which represents if Start was called.
runInEditMode	Allow a specific instance of a MonoBehaviour to run in edit mode (only available in the editor).
useGUILayout	Disabling this lets you skip the GUI layout phase.

Public Methods

CancelInvoke	Cancels all Invoke calls on this MonoBehaviour.
Invoke	Invokes the method methodName in time seconds.
InvokeRepeating	Invokes the method methodName in time seconds, then repeatedly every repeatRate seconds.
IsInvoking	Is any invoke on methodName pending?
StartCoroutine	Starts a Coroutine.
StopAllCoroutines	Stops all coroutines running on this behaviour.
StopCoroutine	Stops the first coroutine named methodName, or the coroutine stored in routine running on this behaviour.

Static Methods

Logs message to the Unity Console (identical to Debug.Log).

Messages

Awake	Unity calls Awake when an enabled script instance is being loaded.
FixedUpdate	Frame-rate independent MonoBehaviour.FixedUpdate message for physics calculations.
LateUpdate	LateUpdate is called every frame, if the Behaviour is enabled.
OnAnimatorIK	Callback for setting up animation IK (inverse kinematics).
OnAnimatorMove	Callback for processing animation movements for modifying root motion.
OnApplicationFocus	Sent to all GameObjects when the player gets or loses focus.
OnApplicationPause	Sent to all GameObjects when the playing application pauses or resumes on losing or regaining focus.
OnApplicationQuit	Sent to all GameObjects before the application quits.
OnAudioFilterRead	If OnAudioFilterRead is implemented, Unity will insert a custom filter into the audio DSP chain.
OnBecameInvisible	OnBecameInvisible is called when the renderer is no longer visible by any camera.
OnBecameVisible	OnBecameVisible is called when the renderer became visible by any camera.
OnCollisionEnter	OnCollisionEnter is called when this collider/rigidbody has begun touching another rigidbody/collider.
OnCollisionEnter2D	Sent when an incoming collider makes contact with this object's collider (2D physics only).
OnCollisionExit	OnCollisionExit is called when this collider/rigidbody has stopped touching another rigidbody/collider.
OnCollisionExit2D	Sent when a collider on another object stops touching this object's collider (2D physics only).
OnCollisionStay	OnCollisionStay is called once per frame for every Collider or Rigidbody that touches another Collider or Rigidbody.
OnCollisionStay2D	Sent each frame where a collider on another object is touching this object's collider (2D physics only).
OnConnectedToServer	Called on the client when you have successfully connected to a server.
OnControllerColliderHit	OnControllerColliderHit is called when the controller hits a collider while performing a Move.
OnDestroy	Destroying the attached Behaviour will result in the game or Scene receiving OnDestroy.
OnDisable	This function is called when the behaviour becomes disabled.
OnDrawGizmos	Implement OnDrawGizmos if you want to draw gizmos that are also pickable and always drawn.
OnDrawGizmosSelected	Implement OnDrawGizmosSelected to draw a gizmo if the object is selected.
OnEnable	This function is called when the object becomes enabled and active.
OnFailedToConnect	Called on the client when a connection attempt fails for some reason.
OnGUI	OnGUI is called for rendering and handling GUI events.
OnJointBreak	Called when a joint attached to the same game object broke.
OnJointBreak2D	Called when a Joint2D attached to the same game object breaks.
OnMouseDown	OnMouseDown is called when the user presses the left mouse button while over the Collider.
OnMouseDrag	OnMouseDrag is called when the user has clicked on a Collider and is still holding down the mouse.
OnMouseEnter	Called when the mouse enters the Collider.
OnMouseExit	Called when the mouse is not any longer over the Collider.
OnMouseOver	Called every frame while the mouse is over the Collider.
OnMouseUp	OnMouseUp is called when the user has released the mouse button.
OnMouseUpAsButton	OnMouseUpAsButton is only called when the mouse is released over the same Collider as it was pressed.
OnParticleCollision	OnParticleCollision is called when a particle hits a Collider.
OnParticleSystemStopped	OnParticleSystemStopped is called when all particles in the system have died, and no new particles will be born. New particles cease to be created either after Stop is called, or when the duration property of a non-looping system has been exceeded.
OnParticleTrigger	OnParticleTrigger is called when any particles in a Particle System meet the conditions in the trigger module.
OnParticleUpdateJobScheduled	OnParticleUpdateJobScheduled is called when a Particle System's built-in update job has been scheduled.
OnPostRender	Event function that Unity calls after a Camera renders the scene.
OnPreCull	Event function that Unity calls before a Camera culls the scene.
OnPreRender	Event function that Unity calls before a Camera renders the scene.
OnRenderImage	Event function that Unity calls after a Camera has finished rendering, that allows you to modify the Camera's final image.
OnRenderObject	OnRenderObject is called after camera has rendered the Scene.
OnServerInitialized	Called on the server whenever a Network.InitializeServer was invoked and has completed.
OnTransformChildrenChanged	This function is called when the list of children of the transform of the GameObject has changed.
OnTransformParentChanged	This function is called when a direct or indirect parent of the transform of the GameObject has changed.
OnTriggerEnter	When a GameObject collides with another GameObject, Unity calls OnTriggerEnter.
OnTriggerEnter2D	Sent when another object enters a trigger collider attached to this object (2D physics only).
OnTriggerExit	OnTriggerExit is called when the Collider other has stopped touching the trigger.
OnTriggerExit2D	Sent when another object leaves a trigger collider attached to this object (2D physics only).
OnTriggerStay	OnTriggerStay is called once per physics update for every Collider other that is touching the trigger.
OnTriggerStay2D	Sent once per physics update when another object is within a trigger collider attached to this object (2D physics only).
OnValidate	Editor-only function that Unity calls when the script is loaded or a value changes in the Inspector.
OnWillRenderObject	OnWillRenderObject is called for each camera if the object is visible and not a UI element.
Reset	Reset to default values.
Start	Start is called on the frame when a script is enabled just before any of the Update methods are called the first time.
Update	Update is called every frame, if the MonoBehaviour is enabled.

Inherited Members

Properties

enabled	Enabled Behaviours are Updated, disabled Behaviours are not.
isActiveAndEnabled	Reports whether a GameObject and its associated Behaviour is active and enabled.
gameObject	The game object this component is attached to. A component is always attached to a game object.
tag	The tag of this game object.
transform	The Transform attached to this GameObject.
hideFlags	Should the object be hidden, saved with the Scene or modifiable by the user?
name	The name of the object.

Public Methods

BroadcastMessage	Calls the method named methodName on every MonoBehaviour in this game object or any of its children.
CompareTag	Checks the GameObject's tag against the defined tag.
GetComponent	Gets a reference to a component of type T on the same GameObject as the component specified.
GetComponentInChildren	Gets a reference to a component of type T on the same GameObject as the component specified, or any child of the GameObject.
GetComponentIndex	Gets the index of the component on its parent GameObject.
GetComponentInParent	Gets a reference to a component of type T on the same GameObject as the component specified, or any parent of the GameObject.
GetComponents	Gets references to all components of type T on the same GameObject as the component specified.
GetComponentsInChildren	Gets references to all components of type T on the same GameObject as the component specified, and any child of the GameObject.
GetComponentsInParent	Gets references to all components of type T on the same GameObject as the component specified, and any parent of the GameObject.
SendMessage	Calls the method named methodName on every MonoBehaviour in this game object.
SendMessageUpwards	Calls the method named methodName on every MonoBehaviour in this game object and on every ancestor of the behaviour.
TryGetComponent	Gets the component of the specified type, if it exists.
GetInstanceID	Gets the instance ID of the object.
ToString	Returns the name of the object.

Static Methods

Destroy	Removes a GameObject, component or asset.
DestroyImmediate	Destroys the object obj immediately. You are strongly recommended to use Destroy instead.
DontDestroyOnLoad	Do not destroy the target Object when loading a new Scene.
FindAnyObjectByType	Retrieves any active loaded object of Type type.
FindFirstObjectByType	Retrieves the first active loaded object of Type type.
FindObjectsByType	Retrieves a list of all loaded objects of Type type.
Instantiate	Clones the object original and returns the clone.
InstantiateAsync	Captures a snapshot of the original object (that must be related to some GameObject) and returns the AsyncInstantiateOperation.

Operators

bool	Does the object exist?
operator !=	Compares if two objects refer to a different object.
operator ==	Compares two object references to see if they refer to the same object.

Is something described here not working as you expect it to? It might be a Known Issue. Please check with the Issue Tracker at issuetracker.unity3d.com.

Scripting API

MonoBehaviour

Success!

Submission failed

Description

Properties

Public Methods

Static Methods

Messages

Inherited Members

Properties

Public Methods

Static Methods

Operators