Adding a share link when using fbdialog to post to a users wall

Question

I'm using FBConnect to post a link to a user's wall. I am using the FBDialog api instead of using graph paths:

[facebook dialog:@"feed" andParams:_params andDelegate:_delegate];

Everything posts correctly except when the wall is viewed, there is no share link, only the like and comment links. I've researched this and figured out that this appears to be unique to using FBDialog.

If the graph path method is used:

[facebook requestWithGraphPath:_path andParams:_params andHttpMethod:@"POST" andDelegate:_delegate];

the share link shows up.

To fix this, I have added a custom link using the actions parameter provided by FBDialog:

SBJSON *jsonWriter = [[SBJSON new] autorelease];

NSDictionary* actionLinks = [NSArray arrayWithObjects:
                             [NSDictionary dictionaryWithObjectsAndKeys:
                              @"Share", @"name", 
                              @"http:???", @"link", 
                              nil], 
                             nil];

NSString *actionLinksStr = [jsonWriter stringWithObject:actionLinks];

[params setObject:@"link" forKey:@"type"];
[params setObject:self.url forKey:@"link"];
[params setObject:self.title forKey:@"name"];
[params setObject:self.caption forKey:@"caption"];
[params setObject:actionLinksStr forKey:@"actions"];

This again, works correctly and creates a share link. The question I have is: What url do I use to share the wall post? Any ideas?

Thanks so much!