Migrating to Gameplay Tag Events

Since 2.0, the Event Identifier and Name nodes are deprecated. They still work in 2.x, but:

• Existing nodes show a deprecation warning when the Blueprint is compiled.
• The nodes no longer appear in the Blueprint context menu.
• They will be removed in a future major version.

Gameplay Tag Events replace all of them with one set of nodes: Register Event, Invoke Event and Wait For Event.

Why

	Event Identifier	Name	Gameplay Tag
Typo-safe	Yes	No	Yes
Needs an asset per event	Yes	No	No
Hierarchy and child-tag listening	No	No	Yes
Data	One fixed type per node	One fixed type per node	Any struct
Unregister one listener	By object	By object	By handle
Async Wait For Event node	No	No	Yes

Node mapping

Deprecated node	Replacement
Register Type Event, Register Type Event Name	Register Event
Invoke Type Event, Invoke Type Event Name	Invoke Event
Unregister Event By Object, Unregister Event Name By Object	Unregister Event By Handle, or Unregister All Events For Object
Unregister Event, Unregister Event Name	Unregister Event By Handle for each listener

Unregister Events, Debug Event Manager and the project settings are not deprecated and work for every event.

Step by step

1. Create a tag for each event. An Event Identifier asset MyEvent or a name "MyEvent" becomes a tag such as Event.MyEvent in Project Settings → Project → GameplayTags.
2. Replace the data with a struct.
   • Simple: send no payload.
   • Int, Float, Bool, String, Vector: create a struct with one variable of that type, for example S_ScoreChanged with Score (Integer).
   • String + Float, String + Int: send the existing StringFloat or StringInt struct, or your own.
   • Payload: move the object's variables into a struct. If you need to send an existing object, add an object reference variable to the struct.
3. Replace the listener. Swap Register Type Event for Register Event with the new tag. In the callback, use Get Instanced Struct Value on Payload to read your struct. Store the returned Handle if you unregister the listener manually.
4. Replace the sender. Swap Invoke Type Event for Invoke Event with the same tag. Connect your struct through Make Instanced Struct to Payload. Optional Target works as before.
5. Replace the unregister calls as shown in the table above.

Migrate both sides of an event together

Tag events, identifier events and named events never reach each other. A listener moved to Register Event is not called by an old Invoke Simple Event, and the other way around.

Example: an Int event

Before, a listener used Register Int Event Name with "ScoreChanged" and the sender used Invoke Int Event Name with the score.

After:

• Tag: Event.Score.Changed.
• Struct: S_ScoreChanged with Score (Integer).
• Listener: Register Event with Event.Score.Changed. The callback reads Payload with Get Instanced Struct Value as S_ScoreChanged and breaks out Score.
• Sender: Invoke Event with Event.Score.Changed, and Make S_ScoreChanged → Make Instanced Struct → Payload.

Events built from runtime names

Named events were sometimes built at runtime, for example "DoorOpened_" + DoorID. With tags, use one tag for the event and tell the instances apart in one of these ways:

• Optional Target: each door registers Event.Door.Opened itself, and the sender passes the door it wants to reach as Optional Target. See Targeting a Listener.
• Payload: send the ID in the struct, and let the listener ignore events with another ID.
• Child tags: if the set of instances is known in advance, add tags such as Event.Door.Opened.Front. A listener on Event.Door.Opened with Include Child Tags receives all of them.

C++

The deprecated functions do not produce C++ compiler warnings in 2.x, but will be removed together with the Blueprint nodes. Replace them in the same way:

Deprecated	Replacement
RegisterIntEvent(this, Identifier, Callback)	RegisterEvent(this, Tag, Callback) with an FTagEventDelegate
InvokeIntEvent(this, Target, Identifier, 42)	InvokeEvent(this, Tag, FInstancedStruct::Make(FScoreChanged{ 42 }), Target)
UnregisterEventByObject(this, Identifier, this)	UnregisterEventByHandle(this, Handle) or UnregisterAllEventsForObject(this, this)

See Using EventDispatcher from C++ for complete examples.