UE4 C++ Set Object Type or Set Collision Channel Type

UE4 C++ Set Object Type or Set Collision Channel Type .cpp

/*
Ok, so you want to change your Object Type (or collision channel) to a custom channel in runtime.
But there's a problem, it seems UE4 doesn't support this yet, but there's a workaround hehe :)

For example, imagine you create the ObjectType Building. 
Now, imagine you want to change the ObjectType of all the StaticMeshComponents of the object OBJECT (from WorldStatic to Building, for example).

You can try something like this:
*/

void MyActor::ChangeMeshesObjectTypeToBuilding()
{
	TArray<UStaticMeshComponent*> meshes; GetComponents<UStaticMeshComponent>(meshes);
	for (UStaticMeshComponent* mesh : meshes)
	{
		mesh->SetCollisionObjectType( ????????? ); //What do I pass here???
	}
}

/*
The ???????? is the problem here. 
StaticMeshComponent has the funcion SetCollisionObjectType(ECollisionChannel channel). But how do I get my Building channel to pass into this function !?!?!?  
For the preset ones you can go ECC_WorldStatic, ECC_WorldDynamic, etc. But for custom ones?

Well, once you have created your custom ObjectType in the editor, UE4 fills one out of the 18 custom ObjectType slots. In C++ you can access the custom slots like this:  ECC_GameTraceChannel1, ECC_GameTraceChannel2, ECC_GameTraceChannel3....

To know in which slot your custom ObjectType is, just check the file Config/DefaultEngine.ini, and search the line containing the ObjectType definition, it would look something like this:

-DefaultChannelResponses=(Channel=ECC_GameTraceChannel3,Name="Building",DefaultResponse=ECR_Block,bTraceType=False,bStaticObject=False)

So finally, using this, in this case, my function would be:
*/

void MyActor::ChangeMeshesObjectTypeToBuilding()
{
	TArray<UStaticMeshComponent*> meshes; GetComponents<UStaticMeshComponent>(meshes);
	for (UStaticMeshComponent* mesh : meshes)
	{
		mesh->SetCollisionObjectType( ECC_GameTraceChannel3 ); //NOW WE KNOW WHAT TO PUT :) 
	}
}

You can now use SetCollisionProfileName(TEXT("SomePreset"));

and if you want it to be more readable , you just need to add #define COLLISION_SOMETHING ECC_GameTraceChannel3 (For example if you want to use channel3) to your project.h file.

so instead of using mesh->SetCollisionObjectType( ECC_GameTraceChannel3 ); , you can use : mesh->SetCollisionObjectType( COLLISION_SOMETHING );