AlamofireImage integration for AsyncDisplayKit

AfnImageCacheForAsdk.swift

//
//  AfnImageCacheForAsdk.swift
//
//  Created by Alexander Dodatko on 4/26/17.
//

import Foundation

import AlamofireImage
import AsyncDisplayKit

public class AfnImageCacheForAsdk: NSObject, ASImageCacheProtocol
{
    public func cachedImage(with URL: URL,
                       callbackQueue: DispatchQueue,
                          completion: @escaping AsyncDisplayKit.ASImageCacherCompletion)
    {
        let result = self.synchronouslyFetchedCachedImage(with: URL)
        
        callbackQueue.async
        {
            completion(result)
        }
    }
    
    public func clearFetchedImageFromCache(with URL: URL)
    {
        let imageCache: AlamofireImage.ImageRequestCache? =
            AlamofireImage.ImageDownloader.default.imageCache
        
        let request = URLRequest(url: URL)
        _ = imageCache?.removeImage(for: request, withIdentifier: nil)
    }
    
    
    public func synchronouslyFetchedCachedImage(with URL: URL) -> ASImageContainerProtocol?
    {
        let imageCache: AlamofireImage.ImageRequestCache? =
            AlamofireImage.ImageDownloader.default.imageCache
        
        let request = URLRequest(url: URL)
        let result = imageCache?.image(for: request, withIdentifier: nil)
        
        return result
    }

}

AfnImageLoaderForAsdk.swift

//
//  AfnImageLoaderForAsdk.swift
//
//  Created by Alexander Dodatko on 4/26/17.
//

import Foundation

import AlamofireImage
import AsyncDisplayKit

public class AfnImageLoaderForAsdk: NSObject, ASImageDownloaderProtocol
{
    private var _pendingRequestMap: [NSUUID : AlamofireImage.RequestReceipt] = [:]
    private var _lock = NSLock()
    
    public func cancelImageDownload(forIdentifier downloadIdentifier: Any)
    {
        let taskId = downloadIdentifier as! NSUUID
        if let receipt = self.receptForTaskWithId(taskId)
        {
            AlamofireImage.ImageDownloader.default.cancelRequest(with: receipt)
        }
        
        self.removeReceptForTaskWithId(taskId)
    }

    public func downloadImage(with URL: URL,
                         callbackQueue: DispatchQueue,
                      downloadProgress: AsyncDisplayKit.ASImageDownloaderProgress?,
                            completion: @escaping AsyncDisplayKit.ASImageDownloaderCompletion)
    -> Any?
    {
        let request = AfnWebImageRequest(path: URL.absoluteString)
        
        let downloadTaskId = NSUUID()
        
        let maybePendingRequestHandle: AlamofireImage.RequestReceipt? =
        AlamofireImage.ImageDownloader.default.download(request)
        {
            (response) in
            
            if let loadedImage = response.result.value
            {
                self.removeReceptForTaskWithId(downloadTaskId)
                completion(loadedImage, nil, downloadTaskId)
            }
        }
        
        if let pendingRequestHandle = maybePendingRequestHandle
        {
            self.addReceipt(pendingRequestHandle, forTaskWithId: downloadTaskId)
            return downloadTaskId
        }
        else
        {
            return nil
        }
    }
    
    
    private func addReceipt(_ receipt: AlamofireImage.RequestReceipt,
         forTaskWithId downloadTaskId: NSUUID)
    {
        self._lock.lock()
        self._pendingRequestMap[downloadTaskId] = receipt
        self._lock.unlock()
    }
    
    private func removeReceptForTaskWithId(_ downloadTaskId: NSUUID)
    {
        self._lock.lock()
        self._pendingRequestMap.removeValue(forKey: downloadTaskId)
        self._lock.unlock()
    }
    
    private func receptForTaskWithId(_ downloadTaskId: NSUUID) -> AlamofireImage.RequestReceipt?
    {
        self._lock.lock()
        let result = self._pendingRequestMap[downloadTaskId]
        self._lock.unlock()
        
        return result
    }
    
}

UsageExample.swift

public class ChatRoomView: NMessengerViewController
{
  // ...
  // ...
  
  // storing as ivars since AsyncDisplayKit absorbs weak references
  private let _imageLoader = AfnImageLoaderForAsdk()
  private let _imageCache  = AfnImageCacheForAsdk()
  
  fileprivate func buildNodeForTextMessage(_ message: ChatMessage) -> GeneralMessengerCell
  {
      // ...
      // ...
    
      let imageLoader = self._imageLoader
      let imageCache  = self._imageCache

      let avatar = ASNetworkImageNode(
                                   cache: imageCache,
                              downloader: imageLoader)

      avatar.defaultImage = UIImage(named: "no-avatar-icon")
      avatar.url = avatarUrl
  }
   
}