text: /*
   * This file is part of the SDWebImage package.
   * (c) Olivier Poitrey <rs@dailymotion.com>
   *
   * For the full copyright and license information, please view the LICENSE
   * file that was distributed with this source code.
   */
  
  #import <Foundation/Foundation.h>
  #import <WebImage/SDWebImageManager.h>
  
  @class SDWebImagePrefetcher;
  
  @protocol SDWebImagePrefetcherDelegate <NSObject>
  
  @optional
  
  /**
   * Called when an image was prefetched.
   *
   * @param imagePrefetcher The current image prefetcher
   * @param imageURL        The image url that was prefetched
   * @param finishedCount   The total number of images that were prefetched (successful or not)
   * @param totalCount      The total number of images that were to be prefetched
   */
  - (void)imagePrefetcher:(SDWebImagePrefetcher *)imagePrefetcher didPrefetchURL:(NSURL *)imageURL finishedCount:(NSUInteger)finishedCount totalCount:(NSUInteger)totalCount;
  
  /**
   * Called when all images are prefetched.
   * @param imagePrefetcher The current image prefetcher
   * @param totalCount      The total number of images that were prefetched (whether successful or not)
   * @param skippedCount    The total number of images that were skipped
   */
  - (void)imagePrefetcher:(SDWebImagePrefetcher *)imagePrefetcher didFinishWithTotalCount:(NSUInteger)totalCount skippedCount:(NSUInteger)skippedCount;
  
  @end
  
  typedef void(^SDWebImagePrefetcherProgressBlock)(NSUInteger noOfFinishedUrls, NSUInteger noOfTotalUrls);
  typedef void(^SDWebImagePrefetcherCompletionBlock)(NSUInteger noOfFinishedUrls, NSUInteger noOfSkippedUrls);
  
  /**
   * Prefetch some URLs in the cache for future use. Images are downloaded in low priority.
   */
  @interface SDWebImagePrefetcher : NSObject
  
  /**
   *  The web image manager
   */
  @property (strong, nonatomic, readonly) SDWebImageManager *manager;
  
  /**
   * Maximum number of URLs to prefetch at the same time. Defaults to 3.
   */
  @property (nonatomic, assign) NSUInteger maxConcurrentDownloads;
  
  /**
   * SDWebImageOptions for prefetcher. Defaults to SDWebImageLowPriority.
   */
  @property (nonatomic, assign) SDWebImageOptions options;
  
  /**
   * Queue options for Prefetcher. Defaults to Main Queue.
   */
  @property (nonatomic, assign) dispatch_queue_t prefetcherQueue;
  
  @property (weak, nonatomic) id <SDWebImagePrefetcherDelegate> delegate;
  
  /**
   * Return the global image prefetcher instance.
   */
  + (SDWebImagePrefetcher *)sharedImagePrefetcher;
  
  /**
   * Allows you to instantiate a prefetcher with any arbitrary image manager.
   */
  - (id)initWithImageManager:(SDWebImageManager *)manager;
  
  /**
   * Assign list of URLs to let SDWebImagePrefetcher to queue the prefetching,
   * currently one image is downloaded at a time,
   * and skips images for failed downloads and proceed to the next image in the list
   *
   * @param urls list of URLs to prefetch
   */
  - (void)prefetchURLs:(NSArray *)urls;
  
  /**
   * Assign list of URLs to let SDWebImagePrefetcher to queue the prefetching,
   * currently one image is downloaded at a time,
   * and skips images for failed downloads and proceed to the next image in the list
   *
   * @param urls            list of URLs to prefetch
   * @param progressBlock   block to be called when progress updates; 
   *                        first parameter is the number of completed (successful or not) requests, 
   *                        second parameter is the total number of images originally requested to be prefetched
   * @param completionBlock block to be called when prefetching is completed
   *                        first param is the number of completed (successful or not) requests,
   *                        second parameter is the number of skipped requests
   */
  - (void)prefetchURLs:(NSArray *)urls progress:(SDWebImagePrefetcherProgressBlock)progressBlock completed:(SDWebImagePrefetcherCompletionBlock)completionBlock;
  
  /**
   * Remove and cancel queued list
   */
  - (void)cancelPrefetching;
  
  
  @end
  