UBehaviorTreeComponent::RegisterMessageObserver

function AIModule Since 4.0

#include "BehaviorTree/BehaviorTreeComponent.h"

Access: public

Description

Sets up an observer that resumes a task's latent execution when a matching FAIMessage is broadcast to this component. Used by tasks waiting on an external system (pathfinding, animation, etc.) to signal completion.

Caveats & Gotchas

• Only takes effect while the task is actually running as a latent operation; calling it for a task that isn't currently executing has no effect.
• A second overload accepts an explicit FAIRequestID so you can match one specific request instead of any message of MessageType — needed when the same task can have multiple outstanding requests.
• Observers registered this way are cleaned up automatically by UnregisterMessageObserversFrom when the task finishes, aborts, or the tree stops.

Signature

void RegisterMessageObserver(const UBTTaskNode* TaskNode, FName MessageType);

Parameters

Name	Type	Description	Default
TaskNode	const UBTTaskNode*	The task whose latent execution should resume when a matching message arrives.	—
MessageType	FName	Identifier of the message to wait for, matched against the Message parameter passed to FAIMessage::Send.	—

Return Type

void

Example

Register observer in a latent task C++

EBTNodeResult::Type UBTTask_WaitForSignal::ExecuteTask(UBehaviorTreeComponent& OwnerComp, uint8* NodeMemory)
{
	OwnerComp.RegisterMessageObserver(this, TEXT("SignalReceived"));
	RequestAsyncSystemToFireSignal();
	return EBTNodeResult::InProgress;
}

Version History

Introduced in: 4.0

Version	Status	Notes
5.6	stable	—

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