How to make a Tickable Object

By default, some objects in Unreal are tickable and some are not. UUserWidget has a NativeTick function, but a lot of other UWidget subclasses are not. Similarly when implementing Subsystem singletons I often want to make them tickable.

Making something tickable is a lot easier than I first thought. If your class implements the FTickableGameObject interface it will automatically be ticked! It does not have to be a subclass of UObject, it can just be a regular struct or class.

This sample code should be all you need to get started:

MyTickableThing.h

#pragma once

#include "CoreMinimal.h"
#include "Tickable.h"

class FMyTickableThing : public FTickableGameObject
{
public:
	// FTickableGameObject Begin
	virtual void Tick( float DeltaTime ) override;
	virtual ETickableTickType GetTickableTickType() const override
	{
		return ETickableTickType::Always;
	}
	virtual TStatId GetStatId() const override
	{
		RETURN_QUICK_DECLARE_CYCLE_STAT( FMyTickableThing, STATGROUP_Tickables );
	}
	virtual bool IsTickableWhenPaused() const
	{
		return true;
	}
	virtual bool IsTickableInEditor() const
	{
		return false;
	}
	// FTickableGameObject End


private:
	// The last frame number we were ticked.
	// We don't want to tick multiple times per frame 
	uint32 LastFrameNumberWeTicked = INDEX_NONE;
};

MyTickableThing.cpp

#include "MyTickableThing.h"

void FMyTickableThing::Tick( float DeltaTime )
{
	if ( LastFrameNumberWeTicked == GFrameCounter )
		return;

	// Do our tick
	// ...

	LastFrameNumberWeTicked = GFrameCounter;
}

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