Added auto release pool to keep memory foot print down when retrieving image from disk in queryDiskCacheForKey

SDWebImage/SDImageCache.m

@@ -194,6 +194,8 @@ static const NSInteger kDefaultCacheMaxCacheAge = 60 * 60 * 24 * 7; // 1 week
     }
 
     dispatch_async(self.ioQueue, ^
+    {
+        @autoreleasepool
         {
             UIImage *diskImage = [UIImage decodedImageWithImage:SDScaledImageForPath(key, [NSData dataWithContentsOfFile:[self cachePathForKey:key]])];
 
@@ -207,6 +209,7 @@ static const NSInteger kDefaultCacheMaxCacheAge = 60 * 60 * 24 * 7; // 1 week
             {
                 doneBlock(diskImage, SDImageCacheTypeDisk);
             });
+        }
     });
 }