added currentDownload Count, to allow someone to see how many operations are left.

SDWebImage/SDWebImageDownloader.h

@@ -62,6 +62,12 @@ typedef void(^SDWebImageDownloaderCompletedBlock)(UIImage *image, NSData *data,
 
 @property (assign, nonatomic) NSInteger maxConcurrentDownloads;
 
+/**
+ * Shows the current amount of downloads that still need to be downloaded
+ */
+
+@property (readonly, nonatomic) NSUInteger currentDownloadCount;
+
 /**
  * Changes download operations execution order. Default value is `SDWebImageDownloaderFIFOExecutionOrder`.
  */

SDWebImage/SDWebImageDownloader.m

@@ -104,6 +104,10 @@ static NSString *const kCompletedCallbackKey = @"completed";
     _downloadQueue.maxConcurrentOperationCount = maxConcurrentDownloads;
 }
 
+- (NSUInteger)currentDownloadCount {
+    return _downloadQueue.operationCount;
+}
+
 - (NSInteger)maxConcurrentDownloads
 {
     return _downloadQueue.maxConcurrentOperationCount;