crash 保护 review by hongmo

@@ -52,9 +52,16 @@
                                        completed:(SDWebImageCompletionWithFinishedBlock)completedBlock
 {
     @try {
+        if ([url isKindOfClass:NSString.class]) {
+            url = [NSURL URLWithString:(NSString *)url];
+        }
+        
+        // Prevents app crashing on argument type error like sending NSNull instead of NSURL
+        if ([url isKindOfClass:NSURL.class]) {
             if ([YHEventReport sharedInstance].isPerformanceTrackEnabled && [YHEventReport sharedInstance].isImagePerformanceTrackEnable){
                 [[YH_EventCollector sharedInstance] timeEventStartWithWebImageDownloadURL:url.absoluteString];
             }
+        }
     } @catch (NSException *exception) {
         YHLog(@"%@ error: %@", self, exception);
     }
@@ -62,7 +69,7 @@
     return [self yher_downloadImageWithURL:url options:options progress:progressBlock completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished, NSURL *imageURL) {
         
         @try {
-            
+            if ([url isKindOfClass:NSURL.class]) {
                 if ([YHEventReport sharedInstance].isPerformanceTrackEnabled && [YHEventReport sharedInstance].isImagePerformanceTrackEnable){
                     if (cacheType == SDImageCacheTypeNone) {//暂时只去下载的图片的时间，过滤掉读缓存的时间
                         if (error) {
@@ -72,6 +79,7 @@
                              }
                     }
                 }
+            }
         } @catch (NSException *exception) {
             YHLog(@"%@ error: %@", self, exception);
         }