Add option to skip retry on download error. (#336)

Author: chenium

Source/Classes/PINRemoteImageManager.h

@@ -57,6 +57,8 @@ typedef NS_OPTIONS(NSUInteger, PINRemoteImageManagerDownloadOptions) {
     PINRemoteImageManagerSaveProcessedImageAsJPEG = 1 << 3,
     /** Ignore cache and force download */
     PINRemoteImageManagerDownloadOptionsIgnoreCache = 1 << 4,
+    /** Skip download retry */
+    PINRemoteImageManagerDownloadOptionsSkipRetry = 1 << 5,
 };
 
 /**

Source/Classes/PINRemoteImageManager.m

@@ -832,7 +832,7 @@ - (NSURLSessionDataTask *)sessionTaskWithURL:(NSURL *)url
                 NSUInteger newNumberOfRetries = 0;
                 [strongSelf lock];
                     PINRemoteImageDownloadTask *task = [strongSelf.tasks objectForKey:key];
-                    if (task.numberOfRetries < PINRemoteImageMaxRetries) {
+                    if (task.numberOfRetries < PINRemoteImageMaxRetries && (options & PINRemoteImageManagerDownloadOptionsSkipRetry) == NO) {
                         retry = YES;
                         newNumberOfRetries = ++task.numberOfRetries;