stickerSelectionControllerDelegate.swift

func stickerSelectionController(_ stickerSelectionController: StickerSelectionController, didSelect sticker: Sticker, with image: UIImage) {
  guard let referenceSize = delegate?.stickerViewControllerReferenceSize(self) else { return }
  
  var model = StickerSpriteModel(sticker: sticker)
  let aspectRatio = referenceSize.width / referenceSize.height
  model.normalizedCenter = CGPoint(x: 0.5, y: 0.5)
  model.normalizedSize = CGSize(width: 0.3, height: 0.3 * aspectRatio)
  delegate?.stickerViewControllerDidFinish(self, stickerModel: model)
  dismiss(animated: true, completion: nil)
}