void ReloadCollectionView()
        {
            var sections = new Collection <ChipSection>()
            {
                new ChipSection(
                    NSBundle.MainBundle.LocalizedString("filter_school_section_title", ""),
                    ViewModel.Schools,
                    ViewModel.ToggleSchoolBookmarkAtIndex
                    ),
                new ChipSection(
                    NSBundle.MainBundle.LocalizedString("filter_school_class_section_title", ""),
                    ViewModel.SchoolClasses,
                    ViewModel.ToggleSchoolClassBookmarkAtIndex
                    ),
                new ChipSection("Lehrer", new ObservableCollection <ChipViewModel>(), null)
            };

            // TODO: observe teacher for changes (make an observable with a static list?)
            foreach (ChipGroupViewModel teacherGroup in ViewModel.TeacherGroups)
            {
                sections.Add(new ChipSection(teacherGroup.Name, teacherGroup.TeacherViewModels, null));
            }

            DataSource = new ChipCollectionViewDataSource(CollectionView, sections);

            Delegate = new ChipCollectionViewDelegate(sections);

            CollectionView.DataSource = DataSource;
            CollectionView.Delegate   = Delegate;
            CollectionView.ReloadData();
        }
        public override void ViewDidLoad()
        {
            base.ViewDidLoad();

            ViewModel = new NewSchoolClassesViewModel();

            var sections = new Collection <ChipSection>()
            {
                new ChipSection(
                    null,
                    ViewModel.SchoolClasses,
                    ViewModel.ToggleSchoolClassBookmarkAtIndex
                    )
            };

            SchoolClassesDataSource   = new ChipCollectionViewDataSource(CollectionView, sections);
            CollectionView.DataSource = SchoolClassesDataSource;
            SchoolClassesDelegate     = new ChipCollectionViewDelegate(sections);
            CollectionView.Delegate   = SchoolClassesDelegate;

            TitleLabel.Text      = NSBundle.MainBundle.LocalizedString("new_school_classes_title", "");
            SubTitleLabel.Text   = NSBundle.MainBundle.LocalizedString("new_school_classes_subtitle", "");
            DoneButtonLabel.Text = NSBundle.MainBundle.LocalizedString("new_school_classses_done_button", "");
        }