Fix that completion block and set image block are called asynchronously in UIVie…

…w+WebCache. Add a more common macro to do current queue check

@@ -99,11 +99,15 @@ typedef void(^SDWebImageNoParamsBlock)(void);
 
 FOUNDATION_EXPORT NSString *const SDWebImageErrorDomain;
 
-#ifndef dispatch_main_async_safe
-#define dispatch_main_async_safe(block)\
-    if (strcmp(dispatch_queue_get_label(DISPATCH_CURRENT_QUEUE_LABEL), dispatch_queue_get_label(dispatch_get_main_queue())) == 0) {\
+#ifndef dispatch_queue_async_safe
+#define dispatch_queue_async_safe(queue, block)\
+    if (strcmp(dispatch_queue_get_label(DISPATCH_CURRENT_QUEUE_LABEL), dispatch_queue_get_label(queue)) == 0) {\
         block();\
     } else {\
-        dispatch_async(dispatch_get_main_queue(), block);\
+        dispatch_async(queue, block);\
     }
 #endif
+
+#ifndef dispatch_main_async_safe
+#define dispatch_main_async_safe(block) dispatch_queue_async_safe(dispatch_get_main_queue(), block)
+#endif

@@ -106,7 +106,7 @@ static char TAG_ACTIVITY_SHOW;
             }
             dispatch_queue_t targetQueue = shouldUseGlobalQueue ? dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0) : dispatch_get_main_queue();
             
-            dispatch_async(targetQueue, ^{
+            dispatch_queue_async_safe(targetQueue, ^{
                 [sself sd_setImage:targetImage imageData:targetData basedOnClassOrViaCustomSetImageBlock:setImageBlock];
                 dispatch_main_async_safe(callCompletedBlockClojure);
             });