Merge pull request #103 from fannheyward/master

Fix warning: "performSelector may cause a leak because its selector is unknown."

@@ -42,7 +42,10 @@ NSString *const SDWebImageDownloadStopNotification = @"SDWebImageDownloadStopNot
     if (NSClassFromString(@"SDNetworkActivityIndicator"))
     {
         
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
         id activityIndicator = [NSClassFromString(@"SDNetworkActivityIndicator") performSelector:NSSelectorFromString(@"sharedActivityIndicator")];
+#pragma clang diagnostic pop
 
         // Remove observer in case it was previously added.
         [[NSNotificationCenter defaultCenter] removeObserver:activityIndicator name:SDWebImageDownloadStartNotification object:nil];