UObject class in Unreal Engine

Iterating over UObjects

The function below can be used for all Run-Time instances of UObject. Iterators in Unreal Engine are always accurate. More info about Iterators in the Iterators handbook

#include "EngineUtils.h"
void AExampleClass::PrintAllObjectsNamesAndClasses()
{
  for (TObjectIterator<UObject> Itr; Itr; ++Itr )
  {
    ClientMessage(Itr->GetName());
    ClientMessage(Itr->GetClass()->GetDesc());
  }
}

• Object iterator is going to iterate over objects in the Pre-PIE world / the Editor World. This is not an issue when the game is running as an independent Game Instance / the editor is closed. Otherwise it can lead to unexpected results.
• Object Iterator does not require a UWorld* Context - so Object Iterator is the way to get the proper context and access the entire living game world even when there's not possible to obtain the World().
• UObject iterator can contain as well as iterate over all components that are inherited from this class, see Get Asset based of Class example. It can also iterate over TObjectIterator<AActor> Itr;, TObjectIterator<ACharacter> Itr; and others.

Get the names of all objects

#include "Kismet/BlueprintFunctionLibrary.h" // Engine
/**
 * Get the names of all objects
 *
 * @param bOutSuccess			If the action was a success or not
 * @param OutInfoMsg		More information about the action's result
 *
 * @return Names of all the objects
 */
UFUNCTION(BlueprintCallable, Category = "Alex Quevillon - Get All Actors Of Class")
static TArray<FString> GetNamesOfAllObjects(bool& bOutSuccess, FString& OutInfoMsg);

#include "Kismet/GameplayStatics.h" // Engine
#include "EngineUtils.h" // Engine
#include "Engine/StaticMeshActor.h" // Engine
	
TArray<FString> UExampleClass::GetNamesOfAllObjects(bool& bOutSuccess, FString& OutInfoMsg)
{
	// New list of names
	TArray<FString> Names = TArray<FString>();

	// Loop through all the objects using TObjectIterator
	// The class in <> is used as filter when getting the objects. This can be any class you want (as long as it's an Object)
	// In this case, we simply use the UObject class directly to get all the possible objects.
	// Also, for objects you don't need to specify a world as they're not only in a world. They're everywhere.
	// But that also means there are a lof of them, you probably want to filter the class you're looking for.
	for (TObjectIterator<UObject> It; It; ++It)
	{
		// Get the real UObject from the Iterator
		UObject* Object = *It;

		// Get the Object's name
		Names.Add(Object->GetName());
	}

	// Return the names
	bOutSuccess = true;
	OutInfoMsg = FString::Printf(TEXT("Get Names Of All Objects Succeeded"));
	return Names;
}

Get Asset based of Class

As UObject is a class from which many Classes is inherited, it may be used for a parameter that allow to transfer any type of its inherited assets, see the code below:

#include "Engine/StaticMesh.h" // Engine
#include "Engine/SkeletalMesh.h" // Engine
#include "Engine/Texture.h" // Engine
#include "Animation/AnimSequence.h" // Engine
#include "Engine/DataTable.h" // Engine
#include "Sound/SoundWave.h" // Engine
UAssetImportData* UExampleClass::GetAssetImportData(UObject* Asset)
{
  if (Cast<UStaticMesh>(Asset) != nullptr) // UStaticMesh
  {
    return Cast<UStaticMesh>(Asset)->AssetImportData;
  }
  else if (Cast<USkeletalMesh>(Asset) != nullptr) // USkeletalMesh
  {
    return Cast<USkeletalMesh>(Asset)->GetAssetImportData();
  }
  else if (Cast<UTexture>(Asset) != nullptr) // UTexture
  {
    return Cast<UTexture>(Asset)->AssetImportData;
  }
  else if (Cast<UAnimSequence>(Asset) != nullptr) // UAnimSequence
  {
    return Cast<UAnimSequence>(Asset)->AssetImportData;
  }
  else if (Cast<UDataTable>(Asset) != nullptr) // UDataTable
  {
    return Cast<UDataTable>(Asset)->AssetImportData;
  }
  else if (Cast<USoundWave>(Asset) != nullptr) // USoundWave
  {
    return Cast<USoundWave>(Asset)->AssetImportData;
  }
  // .. any other asset type inherited from UObject
  return nullptr;
}