Version: 2023.2
LanguageEnglish
  • C#

MonoBehaviour

class in UnityEngine

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Inherits from:Behaviour

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Implemented in:UnityEngine.CoreModule

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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

destroyCancellationTokenCancellation token raised when the MonoBehaviour is destroyed (Read Only).
didAwakeReturns a boolean value which represents if Awake was called.
didStartReturns a boolean value which represents if Start was called.
runInEditModeAllow a specific instance of a MonoBehaviour to run in edit mode (only available in the editor).
useGUILayoutDisabling this lets you skip the GUI layout phase.

Public Methods

CancelInvokeCancels all Invoke calls on this MonoBehaviour.
InvokeInvokes the method methodName in time seconds.
InvokeRepeatingInvokes the method methodName in time seconds, then repeatedly every repeatRate seconds.
IsInvokingIs any invoke on methodName pending?
StartCoroutineStarts a Coroutine.
StopAllCoroutinesStops all coroutines running on this behaviour.
StopCoroutineStops the first coroutine named methodName, or the coroutine stored in routine running on this behaviour.

Static Methods

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

Messages

AwakeUnity calls Awake when an enabled script instance is being loaded.
FixedUpdateFrame-rate independent MonoBehaviour.FixedUpdate message for physics calculations.
LateUpdateLateUpdate is called every frame, if the Behaviour is enabled.
OnAnimatorIKCallback for setting up animation IK (inverse kinematics).
OnAnimatorMoveCallback for processing animation movements for modifying root motion.
OnApplicationFocusSent to all GameObjects when the player gets or loses focus.
OnApplicationPauseSent to all GameObjects when the playing application pauses or resumes on losing or regaining focus.
OnApplicationQuitSent to all GameObjects before the application quits.
OnAudioFilterReadIf OnAudioFilterRead is implemented, Unity will insert a custom filter into the audio DSP chain.
OnBecameInvisibleOnBecameInvisible is called when the renderer is no longer visible by any camera.
OnBecameVisibleOnBecameVisible is called when the renderer became visible by any camera.
OnCollisionEnterOnCollisionEnter is called when this collider/rigidbody has begun touching another rigidbody/collider.
OnCollisionEnter2DSent when an incoming collider makes contact with this object's collider (2D physics only).
OnCollisionExitOnCollisionExit is called when this collider/rigidbody has stopped touching another rigidbody/collider.
OnCollisionExit2DSent when a collider on another object stops touching this object's collider (2D physics only).
OnCollisionStayOnCollisionStay is called once per frame for every Collider or Rigidbody that touches another Collider or Rigidbody.
OnCollisionStay2DSent each frame where a collider on another object is touching this object's collider (2D physics only).
OnConnectedToServerCalled on the client when you have successfully connected to a server.
OnControllerColliderHitOnControllerColliderHit is called when the controller hits a collider while performing a Move.
OnDestroyDestroying the attached Behaviour will result in the game or Scene receiving OnDestroy.
OnDisableThis function is called when the behaviour becomes disabled.
OnDisconnectedFromServerCalled on the client when the connection was lost or you disconnected from the server.
OnDrawGizmosImplement OnDrawGizmos if you want to draw gizmos that are also pickable and always drawn.
OnDrawGizmosSelectedImplement OnDrawGizmosSelected to draw a gizmo if the object is selected.
OnEnableThis function is called when the object becomes enabled and active.
OnFailedToConnectCalled on the client when a connection attempt fails for some reason.
OnFailedToConnectToMasterServerCalled on clients or servers when there is a problem connecting to the MasterServer.
OnGUIOnGUI is called for rendering and handling GUI events.
OnJointBreakCalled when a joint attached to the same game object broke.
OnJointBreak2DCalled when a Joint2D attached to the same game object breaks.
OnMasterServerEventCalled on clients or servers when reporting events from the MasterServer.
OnMouseDown OnMouseDown is called when the user has pressed the mouse button while over the Collider.
OnMouseDragOnMouseDrag is called when the user has clicked on a Collider and is still holding down the mouse.
OnMouseEnterCalled when the mouse enters the Collider.
OnMouseExitCalled when the mouse is not any longer over the Collider.
OnMouseOverCalled every frame while the mouse is over the Collider.
OnMouseUpOnMouseUp is called when the user has released the mouse button.
OnMouseUpAsButtonOnMouseUpAsButton is only called when the mouse is released over the same Collider as it was pressed.
OnNetworkInstantiateCalled on objects which have been network instantiated with Network.Instantiate.
OnParticleCollisionOnParticleCollision is called when a particle hits a Collider.
OnParticleSystemStoppedOnParticleSystemStopped 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.
OnParticleTriggerOnParticleTrigger is called when any particles in a Particle System meet the conditions in the trigger module.
OnParticleUpdateJobScheduledOnParticleUpdateJobScheduled is called when a Particle System's built-in update job has been scheduled.
OnPlayerConnectedCalled on the server whenever a new player has successfully connected.
OnPlayerDisconnectedCalled on the server whenever a player disconnected from the server.
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.
OnRenderObjectOnRenderObject is called after camera has rendered the Scene.
OnSerializeNetworkViewUsed to customize synchronization of variables in a script watched by a network view.
OnServerInitializedCalled on the server whenever a Network.InitializeServer was invoked and has completed.
OnTransformChildrenChangedThis function is called when the list of children of the transform of the GameObject has changed.
OnTransformParentChangedThis function is called when a direct or indirect parent of the transform of the GameObject has changed.
OnTriggerEnterWhen a GameObject collides with another GameObject, Unity calls OnTriggerEnter.
OnTriggerEnter2DSent when another object enters a trigger collider attached to this object (2D physics only).
OnTriggerExitOnTriggerExit is called when the Collider other has stopped touching the trigger.
OnTriggerExit2DSent when another object leaves a trigger collider attached to this object (2D physics only).
OnTriggerStayOnTriggerStay is called once per physics update for every Collider other that is touching the trigger.
OnTriggerStay2DSent each frame where another object is within a trigger collider attached to this object (2D physics only).
OnValidateEditor-only function that Unity calls when the script is loaded or a value changes in the Inspector.
OnWillRenderObjectOnWillRenderObject is called for each camera if the object is visible and not a UI element.
ResetReset to default values.
StartStart is called on the frame when a script is enabled just before any of the Update methods are called the first time.
UpdateUpdate is called every frame, if the MonoBehaviour is enabled.

Inherited Members

Properties

enabledEnabled Behaviours are Updated, disabled Behaviours are not.
isActiveAndEnabledReports whether a GameObject and its associated Behaviour is active and enabled.
gameObjectThe game object this component is attached to. A component is always attached to a game object.
tagThe tag of this game object.
transformThe Transform attached to this GameObject.
hideFlagsShould the object be hidden, saved with the Scene or modifiable by the user?
nameThe name of the object.

Public Methods

BroadcastMessageCalls the method named methodName on every MonoBehaviour in this game object or any of its children.
CompareTagChecks the GameObject's tag against the defined tag.
GetComponentGets a reference to a component of type T on the same GameObject as the component specified.
GetComponentInChildrenGets a reference to a component of type T on the same GameObject as the component specified, or any child of the GameObject.
GetComponentInParentGets a reference to a component of type T on the same GameObject as the component specified, or any parent of the GameObject.
GetComponentsGets references to all components of type T on the same GameObject as the component specified.
GetComponentsInChildrenGets references to all components of type T on the same GameObject as the component specified, and any child of the GameObject.
GetComponentsInParentGets references to all components of type T on the same GameObject as the component specified, and any parent of the GameObject.
SendMessageCalls the method named methodName on every MonoBehaviour in this game object.
SendMessageUpwardsCalls the method named methodName on every MonoBehaviour in this game object and on every ancestor of the behaviour.
TryGetComponentGets the component of the specified type, if it exists.
GetInstanceIDGets the instance ID of the object.
ToStringReturns the name of the object.

Static Methods

DestroyRemoves a GameObject, component or asset.
DestroyImmediateDestroys the object obj immediately. You are strongly recommended to use Destroy instead.
DontDestroyOnLoadDo not destroy the target Object when loading a new Scene.
FindAnyObjectByTypeRetrieves any active loaded object of Type type.
FindFirstObjectByTypeRetrieves the first active loaded object of Type type.
FindObjectsByTypeRetrieves a list of all loaded objects of Type type.
InstantiateClones the object original and returns the clone.

Operators

boolDoes 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.