Example RubyMotion Swipable Cell module

swipable_cell.rb

module SwipeableCell
  ANIMATION_DURATION = 0.2
  MAX_TRANSITION_ALPHA = 0.5
  SWIPE_THRESHOLD = 110
  LONG_SWIPE_THRESHOLD = SWIPE_THRESHOLD + 80
  FADE_IN_DISTANCE = SWIPE_THRESHOLD

  def gestureRecognizer(recognizer,
    shouldRecognizeSimultaneouslyWithGestureRecognizer: other_recognizer)
    return true unless recognizer.is_a? UIPanGestureRecognizer
    # Allow other recognizers to see vertical panning
    Gesture.panning_vertically?(recognizer, content_view)
  end

  def gestureRecognizerShouldBegin(recognizer)
    return true unless recognizer.is_a? UIPanGestureRecognizer
    # Only respond to events if they're panning side to side
    Gesture.panning_horizontally?(recognizer, content_view)
  end

  def on_pan(recognizer)
    current_location = Gesture.location(recognizer, content_view)

    case recognizer.state
    when UIGestureRecognizerStateBegan
      @pan_gesture_start = current_location

    when UIGestureRecognizerStateChanged
      handle_panning horizontal_movement(current_location)

    when UIGestureRecognizerStateEnded, UIGestureRecognizerStateCancelled
      handle_gesture_end horizontal_movement(current_location)
    end
  end

  # rubocop:disable Style/HashSyntax
  def slide_card(location, delay = 0, &completion)
    UIView.animateWithDuration(ANIMATION_DURATION,
      delay: delay,
      options: UIViewAnimationOptionCurveLinear &&
        UIViewAnimationOptionAllowUserInteraction,
      animations: -> { move_card_horizontally(location) },
      completion: -> (_) { completion.call if completion }
    )
  end
  # rubocop:enable Style/HashSyntax

  def slide_card_to_center(&callback)
    slide_card(0, &callback)
  end

  def slide_card_off_screen(direction = :rtl, &callback)
    raise 'Invalid direction' unless [:rtl, :ltr].include? direction

    screen_size = content_view.frame.size.width

    location = direction == :rtl ? -screen_size : screen_size
    slide_card(location, &callback)
    table_screen.swiped_cell = self
  end

  def move_card_horizontally(location)
    move_content_to(location)
    reapply_layout
  end

  def hidden_icons
    {}
  end

  def icon_layout
    raise 'Cell must define icon_layout'
  end

  def move_content_to(location)
    raise 'Cell must define move_content_to'
  end

  def handle_panning(delta)
    slide_card(-delta)
    update_icons(delta)
  end

  private

  def alpha_from_delta(delta)
    return 1 if delta.abs >= FADE_IN_DISTANCE
    (delta.abs / FADE_IN_DISTANCE) * MAX_TRANSITION_ALPHA
  end

  # rubocop:disable Style/HashSyntax
  def connect_to_pan_recognizer
    pan_recognizer =
      UIPanGestureRecognizer.alloc.initWithTarget self, action: 'on_pan:'
    pan_recognizer.delegate = self
    layout.view.addGestureRecognizer pan_recognizer
  end
  # rubocop:enable Style/HashSyntax

  # Right -> Left = Positive delta
  # Left -> Right = Negative delta
  def delta_to_direction(delta)
    delta > 0 ? :rtl : :ltr
  end

  def handle_gesture_end(delta)
  end

  def hide_icon(icon_id)
    icon_layout.get(icon_id).alpha = 0
  end

  def hide_icons(&callback)
    hidden_icons.values.map { |icon| icon[:object_id] }.each do |icon_id|
      # rubocop:disable Style/HashSyntax
      UIView.animateWithDuration(ANIMATION_DURATION,
        animations: -> { hide_icon(icon_id) }
      )
      # rubocop:enable Style/HashSyntax
    end

    rmq.app.delay(ANIMATION_DURATION) { callback.call if callback }
  end

  def hide_inverse_icon(inverse_icon_hash)
    hide_icon inverse_icon_hash[:object_id]
  end

  def horizontal_movement(current_location)
    @pan_gesture_start.x - current_location.x
  end

  def icon_image_name(delta)
    icon_options = hidden_icons[delta_to_direction(delta)]

    return unless icon_options

    return icon_options[:default_image] if delta.abs < SWIPE_THRESHOLD

    if delta.abs < LONG_SWIPE_THRESHOLD || !icon_options[:long_swipe_image]
      return icon_options[:short_swipe_image]
    end

    icon_options[:long_swipe_image]
  end

  def reapply_layout
    content_view.layoutIfNeeded
  end

  def screen_size
    content_view.frame.size.width
  end

  def show_revealing_icon(icon_hash, delta)
    icon = icon_layout.get(icon_hash[:object_id])

    icon.alpha = alpha_from_delta(delta)
    icon.image =
      rmq.image.resource("dashboard/#{icon_image_name(delta)}")
  end

  def update_icons(delta)
    direction = delta_to_direction(delta)
    icon_hash = hidden_icons[direction]
    inverse_icon_hash = hidden_icons[direction == :rtl ? :ltr : :rtl]

    show_revealing_icon(icon_hash, delta) if icon_hash

    return unless inverse_icon_hash

    hide_inverse_icon(inverse_icon_hash)
  end
end