protected function renderBackendView($start, NavigationIterator $iterator = null): string
    {
        $parent = $this->getParent();

        return $this->render(
            new ToolkitTemplateReference(
                'be_bs_tab',
                'html5',
                ToolkitTemplateReference::SCOPE_BACKEND
            ),
            [
                'name'  => $parent ? $parent->bs_tab_name : null,
                'color' => $start ? $this->rotateColor('ce:' . $start->id) : null,
                'error' => $start ? null : $this->translator->trans('ERR.bsTabParentMissing', [], 'contao_default'),
                'title' => $iterator ? $iterator->currentTitle() : null,
            ]
        );
    }
protected function renderBackendView($start, NavigationIterator $iterator = null): string
    {
        $parent = $this->getParent();

        return $this->render(
            new ToolkitTemplateReference(
                'be_bs_tab',
                'html5',
                ToolkitTemplateReference::SCOPE_BACKEND
            ),
            [
                'name'  => $parent ? $parent->bs_tab_name : null,
                'color' => $start ? $this->rotateColor('ce:' . $start->id) : null,
                'error' => $start ? null : $this->translator->trans('ERR.bsTabParentMissing', [], 'contao_default'),
                'title' => $iterator ? $iterator->currentTitle() : null,
            ]
        );
    }
protected function renderBackendView ( $ start , NavigationIterator $ iterator = null ) : string { $ parent = $ this -> getParent ( ) ; return $ this -> render ( new ToolkitTemplateReference ( 'be_bs_tab' , 'html5' , ToolkitTemplateReference :: SCOPE_BACKEND ) , [ 'name' => $ parent ? $ parent -> bs_tab_name : null , 'color' => $ start ? $ this -> rotateColor ( 'ce:' . $ start -> id ) : null , 'error' => $ start ? null : $ this -> translator -> trans ( 'ERR.bsTabParentMissing' , [ ] , 'contao_default' ) , 'title' => $ iterator ? $ iterator -> currentTitle ( ) : null , ] ) ; }
Render the backend view.

@param ContentModel|null  $start    Start element.
@param NavigationIterator $iterator Iterator.

@return string
Render the backend view .