Update to use the delegate mode, let the actual image loader to decide whether to mark failed or not.

SDWebImage/SDImageLoader.h

@@ -85,4 +85,18 @@ FOUNDATION_EXPORT UIImage * _Nullable SDImageLoaderDecodeProgressiveImageData(NS
                                                progress:(nullable SDImageLoaderProgressBlock)progressBlock
                                               completed:(nullable SDImageLoaderCompletedBlock)completedBlock;
 
+
+@optional
+/**
+ Whether the error from image loader should be marked indded un-recoverable or not.
+ If this return YES, failed URL which does not using `SDWebImageRetryFailed` will be blocked into black list. Else not.
+ If does not implements this method, assume always return NO.
+
+ @param url The URL represent the image. Note this may not be a HTTP URL
+ @param error The URL's loading error, from previous `requestImageWithURL:options:context:progress:completed:` completedBlock's error.
+ @return Whether to block this url or not. Return YES to mark this URL as failed.
+ */
+- (BOOL)shouldBlockFailedURLWithURL:(nonnull NSURL *)url
+                              error:(nonnull NSError *)error;
+
 @end

SDWebImage/SDImageLoadersManager.m

@@ -100,4 +100,17 @@
     return nil;
 }
 
+- (BOOL)shouldBlockFailedURLWithURL:(NSURL *)url error:(NSError *)error {
+    NSArray<id<SDImageLoader>> *loaders = self.loaders;
+    for (id<SDImageLoader> loader in loaders.reverseObjectEnumerator) {
+        if (![loader respondsToSelector:@selector(shouldBlockFailedURLWithURL:error:)]) {
+            break;
+        }
+        if ([loader canRequestImageForURL:url]) {
+            return [loader shouldBlockFailedURLWithURL:url error:error];
+        }
+    }
+    return NO;
+}
+
 @end

SDWebImage/SDWebImageDownloader.m

@@ -546,4 +546,25 @@ didReceiveResponse:(NSURLResponse *)response
     return [self downloadImageWithURL:url options:downloaderOptions context:context progress:progressBlock completed:completedBlock];
 }
 
+- (BOOL)shouldBlockFailedURLWithURL:(NSURL *)url error:(NSError *)error {
+    BOOL shouldBlockFailedURL;
+    // Filter the error domain and check error codes
+    if ([error.domain isEqualToString:SDWebImageErrorDomain]) {
+        shouldBlockFailedURL = (   error.code == SDWebImageErrorInvalidURL
+                                || error.code == SDWebImageErrorBadImageData);
+    } else if ([error.domain isEqualToString:NSURLErrorDomain]) {
+        shouldBlockFailedURL = (   error.code != NSURLErrorNotConnectedToInternet
+                                && error.code != NSURLErrorCancelled
+                                && error.code != NSURLErrorTimedOut
+                                && error.code != NSURLErrorInternationalRoamingOff
+                                && error.code != NSURLErrorDataNotAllowed
+                                && error.code != NSURLErrorCannotFindHost
+                                && error.code != NSURLErrorCannotConnectToHost
+                                && error.code != NSURLErrorNetworkConnectionLost);
+    } else {
+        shouldBlockFailedURL = NO;
+    }
+    return shouldBlockFailedURL;
+}
+
 @end

SDWebImage/SDWebImageManager.m

@@ -374,19 +374,8 @@ static id<SDImageLoader> _defaultImageLoader;
     if ([self.delegate respondsToSelector:@selector(imageManager:shouldBlockFailedURL:withError:)]) {
         shouldBlockFailedURL = [self.delegate imageManager:self shouldBlockFailedURL:url withError:error];
     } else {
-        // Filter the error domain and check error codes
+        if ([self.imageLoader respondsToSelector:@selector(shouldBlockFailedURLWithURL:error:)]) {
-        if ([error.domain isEqualToString:SDWebImageErrorDomain]) {
+            shouldBlockFailedURL = [self.imageLoader shouldBlockFailedURLWithURL:url error:error];
-            shouldBlockFailedURL = (   error.code == SDWebImageErrorInvalidURL
-                                    || error.code == SDWebImageErrorBadImageData);
-        } else if ([error.domain isEqualToString:NSURLErrorDomain]) {
-            shouldBlockFailedURL = (   error.code != NSURLErrorNotConnectedToInternet
-                                    && error.code != NSURLErrorCancelled
-                                    && error.code != NSURLErrorTimedOut
-                                    && error.code != NSURLErrorInternationalRoamingOff
-                                    && error.code != NSURLErrorDataNotAllowed
-                                    && error.code != NSURLErrorCannotFindHost
-                                    && error.code != NSURLErrorCannotConnectToHost
-                                    && error.code != NSURLErrorNetworkConnectionLost);
         } else {
             shouldBlockFailedURL = NO;
         }