UGantryAsyncAction_ListenForMessages

ClassGantryCoreBlueprint-visible

#include "Messages/GantryAsyncAction_ListenForMessages.h"

Listen For Messages: a Blueprint node that hears every message sent on a channel, until you cancel it or the object that started it is destroyed.

For example, a scoreboard widget shows each goal:

In the widget's Construct event, add Listen For Messages. Set Channel to MyGame.Message.GoalScored and Payload Type to your S_GoalScored struct.
From On Message Received, call Get Payload on the Async Action pin. Connect a variable of type S_GoalScored to it.
When Get Payload returns true, the variable holds the message: update the scoreboard.

On Message Received fires once per message, with the channel it was sent on. With Match set to Partial, the node also hears every channel under Channel, and the Channel pin says which one.

To stop listening early, call Cancel on the Async Action. Messages are sent with Broadcast Message on the Gantry Message Subsystem (UGantryMessageSubsystem).

Inherits: UCancellableAsyncAction

Properties

Property	Type	Default	Description
`OnMessageReceived`	`FGantryOnMessageReceived`	`()`	Fires once for each message heard, with the channel it was sent on. Read it with Get Payload.
`PayloadType`	`TObjectPtr<UScriptStruct>`	`None`

Functions

`GetPayload`

BlueprintCallableGantry|Messages

Copies the message being received into a struct variable.

Works only inside On Message Received.

Pin	Type	Direction	Description
`OutPayload`	`int32`	out	A variable of the message's struct type, or of a parent struct. Filled in on success.
Return Value	`bool`	out	False outside On Message Received, or when the message is not of that type.

`ListenForMessages`

BlueprintCallableStaticGantry|Messages

Listens for messages on a channel until cancelled or until the listening object is destroyed.

Pin	Type	Direction	Description
`WorldContextObject`	`UObject*`	in	The object listening; the listener ends with it.
`Channel`	`FGameplayTag`	in	The channel, any gameplay tag.
`PayloadType`	`UScriptStruct*`	in	The struct expected. Empty takes any struct, and Get Payload then succeeds only when given the type actually sent.
`Match` = `Exact`	`EGantryTagMatch`	in	Exact, or Partial for the channel and every channel under it.
Return Value	`UGantryAsyncAction_ListenForMessages*`	out	The node, to cancel it.

C++

Public C++ members that Blueprint does not see.

`DECLARE_FUNCTION`

UGantryAsyncAction_ListenForMessages::DECLARE_FUNCTION(execGetPayload)

Get Payload's custom thunk: reads the struct the Blueprint passed in place of OutPayload.

`Activate`

virtual void UGantryAsyncAction_ListenForMessages::Activate() override

Registers the listener.

`SetReadyToDestroy`

virtual void UGantryAsyncAction_ListenForMessages::SetReadyToDestroy() override

Removes the listener.