Waht this iButton_back->SetObserver( ( MCoeControlObserver* ) iCommandObserver ) mean

Hi to all,
Hope you all will be fine. Actually i want to write button handler code in my application. I read for button handler, first derive class from MCoeControlObserver and then implement method like this

class CUsingButtonsAPIAppView : public CCoeControl, public MCoeControlObserver
{
    ....
    ....
        //From MCoeControlObserver
        virtual void HandleControlEventL(CCoeControl* aControl,TCoeEvent aEventType);
..........
.........
 private:
        CAknButton* iFirstButton;
        CAknButton* iSecondButton;
// end of file
void CUsingButtonsAPIAppView::CreateButtonUsingResourceL()
{
    ...........
    ...........
    iFirstButton->SetObserver(this);
    iFirstButton->MakeVisible(ETrue);
    iFirstButton->ActivateL();
}

Here iFirstButton->SetObserver(this); means that you want to implement code in the current class like this

void CUsingButtonsAPIAppView::HandleControlEventL( CCoeControl* aControl, 
                                                  TCoeEvent aEventType )
{
    switch ( aEventType ) 
    { 
        case EEventStateChanged:
        {
            if(aControl == iFirstButton)
            {
                if(iSecondButton->State()->Flags()==KAknButtonStateHasLatchedFrame)
                    iSecondButton->SetCurrentState(KAknButtonTextInsideFrame,ETrue);
            }
            else if(aControl ==iSecondButton)
..........
.........

I want to ask if i set my observer like this

iButton_back->SetObserver( ( MCoeControlObserver* ) iCommandObserver ); 

then what is this mean, is it mean the same as the above line i.e., iFirstButton->SetObserver(this);

My class declaration is like this

class CHelloWorldContainer : public CCoeControl
	{
public:
	// constructors and destructor
	CHelloWorldContainer();
	static CHelloWorldContainer* NewL( 
		const TRect& aRect, 
		const CCoeControl* aParent, 
		MEikCommandObserver* aCommandObserver );
.........
.........
private:
	void InitializeControlsL();
	void LayoutControls();
	CCoeControl* iFocusControl;
	MEikCommandObserver* iCommandObserver;
private: 
	CEikLabel* iLabel_frequency;
	CEikFloatingPointEditor* iFloatingPointEditor_frequency;
	CAknButton* iButton_back;
	CAknButton* iButton_forward;
	CAknButton* iButton_record;
//end of file
void CHelloWorldContainer::ConstructL( 
		const TRect& aRect, 
		const CCoeControl* aParent, 
		MEikCommandObserver* aCommandObserver )
	{
	if ( aParent == NULL )
	    {
		CreateWindowL();
	    }
	else
	    {
	    SetContainerWindowL( *aParent );
	    }
	iFocusControl = NULL;
	iCommandObserver = aCommandObserver;
	InitializeControlsL();
	SetRect( aRect );
	ActivateL();
	// [[[ begin generated region: do not modify [Post-ActivateL initializations]
	// ]]] end generated region [Post-ActivateL initializations]
	
	}
void CHelloWorldContainer::InitializeControlsL()
	{
         ..............
         ..............
         iButton_back->ConstructFromResourceL ( R_HELLO_WORLD_CONTAINER_BUTTON_BACK );
	
	iButton_back->SetContainerWindowL ( *this );
	iButton_back->SetRect ( TRect ( 
								TPoint ( 6, 83 ) , 
								TSize ( 67, 46 ) )  
								 ) ; 
	iButton_back->SetObserver( ( MCoeControlObserver* ) iCommandObserver ); 
        }

As you can see that my class is not derived from MCoeControlObserver, So i want to ask in this case can i write button handler ? or i should modify my code i.e., derived my class from MCoeControlObserver and provide
virtual void HandleControlEventL(CCoeControl* aControl,TCoeEvent aEventType);

and then modify this line
iButton_back->SetObserver( ( MCoeControlObserver* ) iCommandObserver );

to

iButton_back->SetObserver( this );

Thanks