doubt about the behavior of std :: swap

Note:

Reading the answers to this question: How does std :: move work? In the case of std :: move does not move, I generated this doubt, in case it is not a problem in a code that I need to solve, but rather in question the behavior of std :: move, but, of std :: swap. To imagine a use case for the code below, one might think that v_note is a vector of tabs, and that the class in which it belongs manipulates the insertion, removal, and get (get) of the tabs, note_counter is incremented in function insertChild always pointing to the v_note index that has not yet been initialized, and is decremented by the remove function, and Widget * will be a any widget that will be nested the tab, for example, a text field or an image area. p>

Doubt:

Regarding the remove function, std :: swap performs what I'm hoping for ?, I say the remove function does the following:

The code runs normally, the debug shows that the pointers that were 'swapped' by std :: swap are actually null, and my doubt goes right there, with this sort of sorting technique I mentioned, it generates or can I generate a dangling pointer?

Code:

void attach( Widget* parent ){ ... }
void insertChild( Widget* child ){ ... }

void remove( const WidgetID& index )
{
    //analizo se index está dentro do range de abas inicializadas
    if( index >= 0 && index < note_counter )
    {
       //libero os recursos do widget aninhado a minha aba
        v_note[ index ]->Destroy(); 
        delete v_note[ index ];
        v_note[ index ] = nullptr;

        //Ordenação simples    
        if( note_counter > 1 )
        {
            for( size_t i = 0; i < note_counter - 1; i++ )
            {
                for( size_t j = 1; j < note_counter; j++ )
                {
                    if( v_note[ i ] == nullptr && v_note[ j ] != nullptr )
                    {
                        //Dúvida
                        std::swap( v_note[ i ], v_note[ j ] );
                    }
                }
           }
       }
       //decrementa o contador e reordena as ID's 
       if( note_counter > 0 ){ note_counter-= 1; }
       for( size_t i = 0; i < m_counter; i++ )
       {
           if( v_note[ i ] != nullptr ){ v_note[ i ]->SetID( i ); }  
   }
}