Unreal Engine 5 · Blueprint → C++
Implement an Interface in Unreal Engine 5 C++UE Docs
To implement an interface in C++, add the I-class to your class's inheritance list (public IMyInterface) and override the function as Interact_Implementation, not Interact.
Blueprint node & C++ equivalent
// .h
class AMyActor : public AActor, public IMyInterface
{
GENERATED_BODY()
virtual void Interact_Implementation() override;
};
// .cpp
void AMyActor::Interact_Implementation() { /* ... */ }How to implement an interface on an actor
In the header, list the interface alongside your base class: class AMyActor : public AActor, public IMyInterface. The actor now satisfies the interface contract and the reflection system records that AMyActor implements UMyInterface.
Because the interface function was declared BlueprintNativeEvent, you override Interact_Implementation() rather than Interact(). The engine generates the non-suffixed Interact thunk that dispatches to your implementation or to a Blueprint override.
The .h and .cpp split
The header declares virtual void Interact_Implementation() override;. The override keyword ensures you match the interface signature exactly and catches typos at compile time. The .cpp then defines the body: void AMyActor::Interact_Implementation() { /* ... */ }.
This is the C++ equivalent of dropping into a Blueprint Interface event in the Blueprint editor and adding nodes to its graph.
Common mistakes
Overriding Interact() instead of Interact_Implementation() is the most frequent error and usually produces a function that never gets called. For BlueprintNativeEvent and BlueprintImplementableEvent interface functions, always override the _Implementation variant.
Frequently asked questions
Why do I override _Implementation instead of the interface function directly?+
For BlueprintNativeEvent functions the engine generates the base function as a dispatcher, so your C++ logic must live in Interact_Implementation. Overriding the plain Interact would hide the dispatcher and break Blueprint overrides.
How do I make an actor implement multiple interfaces in C++?+
Add each interface to the inheritance list, for example public AActor, public IMyInterface, public IOtherInterface, and override the relevant _Implementation function from each.
Do I need to call Super in an interface _Implementation override?+
Only if a parent class provides a meaningful base implementation you want to extend. Interface defaults are usually empty, so a Super:: call is optional unless your hierarchy defines one.