facebook - iOS deep linking (case : share a link to feed, not open graph)

Question

We share our post link to Facebook like below :

[FBRequestConnection startWithGraphPath:@"me/feed"
                                         parameters:aDic
                                         HTTPMethod:@"POST"
                                  completionHandler:^(FBRequestConnection *connection, id result, NSError *error){
                                      if (error) {
                                          NSLog(@"error: domain = %@, code = %d", error.domain, error.code);
                                          failure(error);
                                      } else {
                                          NSLog(@"Published order action: %@", [result objectForKey:@"id"]);
                                          success([result objectForKey:@"id"]);
                                      }
                                  }];

We tried two parameter cases :

case 1 : set target with "url"

caption = "https://fanme.so/mf9nlL";
message = "...";
name = "...";
picture = "https://stream.fanme.in/images/icon.png";
url = "https://thefan.me/170/788120";

case 2 : set target with "link"

caption = "https://fanme.so/mf9nlL";
link = "https://thefan.me/170/788120";
message = "...";
name = "...";
picture = "https://stream.fanme.in/images/icon.png";

In case 1, deep linking is OK but targetURL(that we parse in AppDelegate) is the url in "picture" key.

In case 2, deep linking is not working. Link in iOS FB App doesn't launch our iOS App. But we can find out targetURL is OK with the url in "link" key (through Facebook website test).

We want to know why "picture" set to targetURL instead of "url" in case 1.

We are using iOS Facebook SDK 3.5 now. We need some help. Thanks.