let controller = JoGalleryController()
controller.register(JoGalleryCell.self, forCellWithReuseIdentifier: ...)
controller.delegate = ...
controller.dataSource = ...

controller.present(from: VC, toItem: indexPath)

func galleryController(_ galleryController: JoGalleryController, numberOfItemsInSection section: Int) -> Int {
    return ...
}

func galleryController(_ galleryController: JoGalleryController, cellForItemAt indexPath: IndexPath) -> JoGalleryCell{

    let cell = galleryController.dequeueReusableCell(withReuseIdentifier: ...), for: indexPath)
    ...
    return cell
}

func presentForTransitioning(in galleryController: JoGalleryController, openAt indexPath: IndexPath) -> JoGalleryLocationAttributes? {
    ...
    return (view, content)
}

func dismissForTransitioning(in galleryController: JoGalleryController, closeAt indexPath: IndexPath) -> JoGalleryLocationAttributes? {
    ...
    return (view, content)
}

func galleryBeginTransforming(in galleryController: JoGalleryController, atIndex indexPath: IndexPath) -> UIView? {
    ...
    return locationView
}

func galleryDidEndTransforming(in galleryController: JoGalleryController, atIndex indexPath: IndexPath, with thresholdValue: CGFloat) -> UIView? {
    ...
    return locationView
}

func gallery(_ galleryController: JoGalleryController, scrolDidDisplay cell: JoGalleryCell, forItemAt indexPath: IndexPath, oldItemFrom oldIndexPath: IndexPath) {
    // scroll to location
    ...
}