button_cell.rb

class ButtonCell < PM::CollectionViewCell

  def setup(data_cell, _)
    super.tap do
      @imageview.image = data_cell[:image].uiimage if data_cell.has_key?(:image)
      @label.text = data_cell[:title] if data_cell.has_key?(:title)
    end
  end

  def on_created
    apply_style :button

    @imageview = append!(UIImageView, :imageview)
    @imageview.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth
    @label = append!(UILabel, :label)
  end

end

collectionscreen.rb

class HomeScreen < PM::CollectionScreen

  collection_layout UICollectionViewFlowLayout,
                    direction: :vertical,
                    minimum_line_spacing: 0,
                    minimum_interitem_spacing: 0,
                    item_size: [256, 256]

  cell_classes button_cell: ButtonCell

  stylesheet HomeScreenStylesheet

  def collection_data
    [
      [
        {
          image: 'horaire',
          title: :class_schedule._,
          cell_identifier: :button_cell,
          action: -> {
            open ScheduleScreen.new
          }
        },
        {
          image: 'jdc',
          title: :timetable._,
          cell_identifier: :button_cell,
          action: -> {
            open TimetableScreen.new
          }
        },
        # and so on
      ]
    ]
  end

  def will_appear
    find(UICollectionView).style do |st|
      st.frame = { l: 0, t: 50, w: device.screen_width, h: device.screen_height - 50 }
    end
  end

end