How to delete object using blueprints (not actor)

Question

Ok I've created some class which inherits from UObject. I can created it in level BP (using Construct object node) and store reference in my BP variable. When I'm creating object I'm setting Outer as self. So level BP owning newly created object. Now my question is how to delete this object from memory? I tried to set BP variable to null but it seems that I need to destroy level to release this object. Any idea how to do it without destorying level?

Answer 1

I have no access to UE4 at this moment but I hope this can help/hint you to a right direction:

UObjects are managed by the garbage collector. To create a UObject appropriately, use NewObject(), NewNamedObject() and ConstructObject(). It is possible to configure the way UObjects will be handled by garbage collector at the time of creation with Object Flags enumeration. (If you like to learn more about UObject Instance Creation, you can go here: hhttps://docs.unrealengine.com/latest/INT/Programming/UnrealArchitecture/Objects/Creation/index.html )

This way, you should not call new or delete on UObjects. If UObject is no longer needed, it usually means that there are no references to it (this may, however differ, depending on the context and garbage collection flags used at the moment of UObject creation). In this situation, you can run ForceGarbageCollection() function:

GetWorld()->ForceGarbageCollection(true);

Please note, that calling this method may cause crashes in some situations, particularly when object is already being destroyed by garbage collector or has a value of null.

Also, if you like to learn more about Unreal Object Handling, you can go here: hhttps://docs.unrealengine.com/latest/INT/Programming/UnrealArchitecture/Objects/Optimizations/index.html

Credit : https://answers.unrealengine.com/questions/219430/explicitely-delete-a-uobject.html

Ps. StackOverflow doesn't allow me to post more than two links because I don't have enough reputation ... so remove the first 'h' from my broken links, it'll work.

Answer 2

I managed to resolve this, I also got some clues given on unreal answer hub: https://answers.unrealengine.com/questions/337525/how-to-delete-object-using-blueprints.html

So basically answer is: set reference variable to null, and at some moment GC will release it. But don't expect to have this instantly.