let gallery = DKPhotoGallery()
gallery.singleTapMode = .dismiss
gallery.items = self.items
gallery.presentingFromImageView = self.imageView
gallery.presentationIndex = 0

gallery.finishedBlock = { dismissIndex, dismissItem in
    if item == dismissItem {
        return imageView
    } else {
        return nil
    }
}

self.present(photoGallery: gallery)

@objc
open class DKPhotoGalleryItem: NSObject {
    
    /// The image to be set initially, until the image request finishes.
    open var thumbnail: UIImage?
    
    open var image: UIImage?
    open var imageURL: URL?
    
    open var videoURL: URL?

    /// iOS 11 or higher required.
    @objc open var pdfURL: URL?
    
    /**
     DKPhotoGallery will automatically decide whether to create ImagePreview or PlayerPreview via the mediaType of the asset.
     
     See more: DKPhotoPreviewFactory.swift
     */
    open var asset: PHAsset?
    open var assetLocalIdentifier: String?
    
    /**
     Used for some optional features.
     
     For ImagePreview, you can enable the original image download feature with a key named DKPhotoGalleryItemExtraInfoKeyRemoteImageOriginalURL.
     */
    open var extraInfo: [String: Any]?
}

let item = DKPhotoGalleryItem(imageURL: URL(string:"https://sz-preview.oss-cn-hangzhou.aliyuncs.com/pics/10003/b29259d837d4aaeef4b33c9dbc964a5b?x-oss-process=image/resize,m_lfit,h_512,w_512/quality,Q_80")!)
item.extraInfo = [
    DKPhotoGalleryItemExtraInfoKeyRemoteImageOriginalURL: URL(string:"https://sz-preview.oss-cn-hangzhou.aliyuncs.com/pics/10003/b29259d837d4aaeef4b33c9dbc964a5b")!
]

DKPhotoGalleryResource.customLocalizationBlock = { title in
    if title == "preview.image.longPress.cancel" {
        return "This is a test."
    } else {
        return nil
    }
}